diff --git a/src/components/clinician/history-sections.tsx b/src/components/clinician/history-sections.tsx
index 308f74ea4..dd6a25138 100644
--- a/src/components/clinician/history-sections.tsx
+++ b/src/components/clinician/history-sections.tsx
@@ -26,6 +26,7 @@ import {
   type LeafScope,
   type Translate,
 } from "./report-sections";
+import { withLabUnit } from "@/lib/labs/dimensionless";
 
 /** Join the parts of a composed value, dropping the ones with nothing in. */
 function compose(parts: Array<string | null | undefined>): string {
@@ -73,7 +74,7 @@ export function LabResultsSection({
         const qualitative = lab.value === null;
         const reading = qualitative
           ? lab.valueText
-          : `${fmtLab(lab.value as number, lab.sourceValue)} ${lab.unit}`.trim();
+          : withLabUnit(fmtLab(lab.value as number, lab.sourceValue), lab.unit);
         const range = (
           low: number | null,
           high: number | null,
diff --git a/src/components/insights/labs-changes-card.tsx b/src/components/insights/labs-changes-card.tsx
index 8ed2a69dc..30a8e146a 100644
--- a/src/components/insights/labs-changes-card.tsx
+++ b/src/components/insights/labs-changes-card.tsx
@@ -11,6 +11,7 @@ import { queryKeys } from "@/lib/query-keys";
 import { SectionHeading } from "@/components/ui/section-heading";
 import type { LabChange } from "@/lib/insights/labs-changes";
 import { InsightSectionCard } from "./insight-section-card";
+import { withLabUnit } from "@/lib/labs/dimensionless";
 
 /**
  * v1.25 — "what changed since your last panel" card.
@@ -81,7 +82,7 @@ export function LabsChangesCard({
           const signedDelta =
             c.direction === "flat"
               ? t("insights.labsChanges.directionFlat")
-              : `${c.delta > 0 ? "+" : ""}${c.delta} ${c.unit}`.trim();
+              : withLabUnit(`${c.delta > 0 ? "+" : ""}${c.delta}`, c.unit);
           return (
             <div
               key={c.analyte}
@@ -93,7 +94,7 @@ export function LabsChangesCard({
                   {c.analyte}
                 </p>
                 <p className="text-muted-foreground text-xs">
-                  {`${c.latest} ${c.unit}`.trim()}
+                  {withLabUnit(String(c.latest), c.unit)}
                   {labelKey ? ` · ${t(labelKey)}` : ""}
                 </p>
               </div>
diff --git a/src/components/labs/biomarker-manager.tsx b/src/components/labs/biomarker-manager.tsx
index f204f0842..c69d11aba 100644
--- a/src/components/labs/biomarker-manager.tsx
+++ b/src/components/labs/biomarker-manager.tsx
@@ -24,6 +24,8 @@ import { BiomarkerForm } from "./biomarker-form";
 import { BiomarkerMergeSheet } from "./biomarker-merge-sheet";
 import type { BiomarkerDto, BiomarkerListResponse } from "./types";
 import { useLabNumber } from "./use-lab-format";
+import { withLabUnit } from "@/lib/labs/dimensionless";
+import { LabUnitName } from "./lab-unit-input";
 
 /**
  * v1.18.1 — the Biomarker catalog manager. v1.22 — compact editable rows.
@@ -124,11 +126,11 @@ export function BiomarkerManager() {
         <div className="min-w-0 flex-1">
           <div className="flex flex-wrap items-baseline gap-x-2">
             <span className="truncate text-sm font-medium">{marker.name}</span>
-            <span className="text-muted-foreground text-xs">{marker.unit}</span>
+            <LabUnitName unit={marker.unit} />
           </div>
           <p className="text-muted-foreground text-xs">
             {range
-              ? `${t("labs.referenceLabel")} ${range} ${marker.unit}`
+              ? `${t("labs.referenceLabel")} ${withLabUnit(range, marker.unit)}`
               : t("labs.biomarker.noRange")}
             {marker.panel ? ` · ${marker.panel}` : ""}
           </p>
diff --git a/src/components/labs/biomarker-merge-sheet.tsx b/src/components/labs/biomarker-merge-sheet.tsx
index 0853b410b..721af3157 100644
--- a/src/components/labs/biomarker-merge-sheet.tsx
+++ b/src/components/labs/biomarker-merge-sheet.tsx
@@ -28,6 +28,7 @@ import { useTranslations } from "@/lib/i18n/context";
 import { queryKeys } from "@/lib/query-keys";
 
 import type { BiomarkerDto, BiomarkerMergeResultDto } from "./types";
+import { labUnitLabel } from "@/lib/labs/dimensionless";
 
 /** The most sources one merge takes, matching the server. */
 const MAX_SOURCES = 10;
@@ -166,7 +167,7 @@ export function BiomarkerMergeSheet({
           <p className="text-sm">
             {tCount("labs.merge.previewSummary", preview.movedReadings, {
               name: preview.target.name,
-              unit: preview.target.unit,
+              unit: labUnitLabel(preview.target.unit, t),
             })}
           </p>
           <ul className="space-y-2">
@@ -178,7 +179,7 @@ export function BiomarkerMergeSheet({
                 <p className="text-sm font-medium break-words">
                   {source.name}{" "}
                   <span className="text-muted-foreground text-xs font-normal">
-                    {source.unit}
+                    {labUnitLabel(source.unit, t)}
                   </span>
                 </p>
                 <p
@@ -190,8 +191,8 @@ export function BiomarkerMergeSheet({
                 >
                   {source.conversion === "refused"
                     ? t("labs.merge.refused", {
-                        unit: source.unit,
-                        targetUnit: preview.target.unit,
+                        unit: labUnitLabel(source.unit, t),
+                        targetUnit: labUnitLabel(preview.target.unit, t),
                       })
                     : source.conversion === "converted"
                       ? tCount("labs.merge.converted", source.readingCount, {
@@ -247,7 +248,7 @@ export function BiomarkerMergeSheet({
                       {marker.name}
                     </span>
                     <span className="text-muted-foreground shrink-0 text-xs">
-                      {marker.unit}
+                      {labUnitLabel(marker.unit, t)}
                     </span>
                   </label>
                 </li>
diff --git a/src/components/labs/lab-biomarker-detail.tsx b/src/components/labs/lab-biomarker-detail.tsx
index 67978895b..cfff0826d 100644
--- a/src/components/labs/lab-biomarker-detail.tsx
+++ b/src/components/labs/lab-biomarker-detail.tsx
@@ -61,6 +61,7 @@ import type {
   LabResultDto,
   LabResultListResponse,
 } from "./types";
+import { labUnitLabel, labUnitText } from "@/lib/labs/dimensionless";
 
 // v1.18.11 — defer the recharts biomarker chart through
 // `next/dynamic` so recharts is off `/labs/[biomarkerId]`'s first-load JS.
@@ -426,7 +427,7 @@ export function LabBiomarkerDetail({ biomarkerId }: { biomarkerId: string }) {
           one description line every page header carries. */}
       {marker?.unit ? (
         <p className="text-muted-foreground text-sm">
-          {marker.unit}
+          {labUnitLabel(marker.unit, t)}
           {marker.panel ? ` · ${marker.panel}` : ""}
         </p>
       ) : null}
@@ -492,7 +493,7 @@ export function LabBiomarkerDetail({ biomarkerId }: { biomarkerId: string }) {
               numeric readings, mirroring the metric sub-pages. */}
           <MetricStatStrip
             summary={summary}
-            unit={marker?.unit ?? latest?.unit ?? ""}
+            unit={labUnitText(marker?.unit ?? latest?.unit)}
             seriesLabel={marker?.name}
             icon={FlaskConical}
           />
@@ -500,7 +501,7 @@ export function LabBiomarkerDetail({ biomarkerId }: { biomarkerId: string }) {
             <CardContent>
               <LabBiomarkerChart
                 readings={readings}
-                unit={marker?.unit ?? latest?.unit ?? ""}
+                unit={labUnitText(marker?.unit ?? latest?.unit)}
                 lowerBound={marker?.lowerBound ?? null}
                 upperBound={marker?.upperBound ?? null}
               />
@@ -508,7 +509,7 @@ export function LabBiomarkerDetail({ biomarkerId }: { biomarkerId: string }) {
           </Card>
           <LabTrendCard
             trend={marker?.trend}
-            unit={marker?.unit ?? latest?.unit ?? ""}
+            unit={labUnitText(marker?.unit ?? latest?.unit)}
           />
         </>
       )}
diff --git a/src/components/labs/lab-form.tsx b/src/components/labs/lab-form.tsx
index b75b4f90b..83652c303 100644
--- a/src/components/labs/lab-form.tsx
+++ b/src/components/labs/lab-form.tsx
@@ -39,6 +39,11 @@ import type {
   BiomarkerListResponse,
   LabResultDto,
 } from "./types";
+import {
+  labUnitLabel,
+  labUnitText,
+  withLabUnit,
+} from "@/lib/labs/dimensionless";
 
 const NOTE_MAX_LENGTH = 2000;
 const DEFINE_NEW = "__define_new__";
@@ -330,9 +335,8 @@ export function LabForm({
     ? formatReferenceRange(selected.lowerBound, selected.upperBound, labNumber)
     : "";
 
-  // What the typed string resolved to, shown back so the user can see whether
-  // a window was read out of it before the reading is saved. When none was,
-  // the hint says the text is kept as written rather than staying silent.
+  // What the typed string resolved to, shown back before the save. When no
+  // window was read out of it, the hint says the text stays as written.
   const parsedSourceRange = parseReferenceRange(sourceRange, selected?.unit);
   const sourceRangeHint = parsedSourceRange
     ? isUnreadableRange(parsedSourceRange)
@@ -341,7 +345,7 @@ export function LabForm({
           parsedSourceRange.low,
           parsedSourceRange.high,
           labNumber,
-        )} ${selected?.unit ?? ""}`.trim()
+        )} ${labUnitText(selected?.unit)}`.trim()
     : "";
 
   const footerNode = (
@@ -406,7 +410,7 @@ export function LabForm({
             <SelectContent>
               {markers.map((m) => (
                 <SelectItem key={m.id} value={m.id}>
-                  {m.name} · {m.unit}
+                  {m.name} · {labUnitLabel(m.unit, t)}
                 </SelectItem>
               ))}
               {!lockedBiomarkerId ? (
@@ -457,7 +461,7 @@ export function LabForm({
                   {selected ? (
                     <span className="text-muted-foreground font-normal">
                       {" "}
-                      ({selected.unit})
+                      ({labUnitLabel(selected.unit, t)})
                     </span>
                   ) : null}
                 </Label>
@@ -515,7 +519,8 @@ export function LabForm({
 
         {resultType === "numeric" && selected && referenceText ? (
           <p className="text-muted-foreground text-xs">
-            {t("labs.referenceLabel")} {referenceText} {selected.unit}
+            {t("labs.referenceLabel")}{" "}
+            {withLabUnit(referenceText, selected.unit)}
           </p>
         ) : null}
 
diff --git a/src/components/labs/lab-history-list.tsx b/src/components/labs/lab-history-list.tsx
index cd794a430..130e85faa 100644
--- a/src/components/labs/lab-history-list.tsx
+++ b/src/components/labs/lab-history-list.tsx
@@ -46,6 +46,7 @@ import {
 } from "./lab-result-related-links";
 import type { LabResultDto } from "./types";
 import { useLabDate, useLabNumber } from "./use-lab-format";
+import { labUnitText } from "@/lib/labs/dimensionless";
 
 const NOTE_MAX_LENGTH = 2000;
 
@@ -103,7 +104,7 @@ export function LabHistoryList({ readings }: { readings: LabResultDto[] }) {
         reading.value === null
           ? (reading.valueText ?? "")
           : labNumber(reading.value, reading.sourceValue),
-      unit: reading.value === null ? undefined : reading.unit,
+      unit: reading.value === null ? undefined : labUnitText(reading.unit),
       compare: before
         ? {
             label: t("day.previousReading", { date: labDate(before.takenAt) }),
diff --git a/src/components/labs/lab-list.tsx b/src/components/labs/lab-list.tsx
index d3219e0cd..43ddc437a 100644
--- a/src/components/labs/lab-list.tsx
+++ b/src/components/labs/lab-list.tsx
@@ -31,6 +31,7 @@ import type {
   LabOverviewResponse,
   LabResultDto,
 } from "./types";
+import { labUnitLabel } from "@/lib/labs/dimensionless";
 
 interface MarkerGroup {
   /** Stable group key: `bm:<biomarkerId>`, or `analyte:<lower>` for legacy rows. */
@@ -39,6 +40,7 @@ interface MarkerGroup {
   biomarkerId: string | null;
   analyte: string;
   panel: string | null;
+  /** The marker's unit as the card names it ("No unit" for a ratio). */
   unit: string;
   /** Every live reading of the marker, counted by the server. */
   count: number;
@@ -53,13 +55,16 @@ interface MarkerGroup {
  * inert until the backfill links them. The server already orders by the
  * newest reading.
  */
-function toGroups(markers: LabOverviewMarkerDto[]): MarkerGroup[] {
+function toGroups(
+  markers: LabOverviewMarkerDto[],
+  t: (key: string) => string,
+): MarkerGroup[] {
   return markers.map((marker) => ({
     key: marker.key,
     biomarkerId: marker.latest.biomarkerId,
     analyte: marker.latest.analyte,
     panel: marker.latest.panel,
-    unit: marker.latest.unit,
+    unit: labUnitLabel(marker.latest.unit, t),
     count: marker.count,
     trend: marker.trend,
     latest: marker.latest,
@@ -152,7 +157,7 @@ export function LabList({
   });
 
   const groups = useMemo(() => {
-    const base = toGroups(data?.markers ?? []);
+    const base = toGroups(data?.markers ?? [], t);
     // v1.18.6 — honour the user's Labs sort choice. The server
     // order is most-recent-first; `recentAsc` reverses, the alpha
     // options sort by analyte name (#43), and `manual` applies the persisted
@@ -173,7 +178,7 @@ export function LabList({
       return applyOrder(base, prefs.order, (g) => g.biomarkerId ?? g.key);
     }
     return base;
-  }, [data?.markers, prefs.sortDir, prefs.order]);
+  }, [data?.markers, prefs.sortDir, prefs.order, t]);
 
   const listEmpty = !isLoading && !isError && groups.length === 0;
   useEffect(() => {
diff --git a/src/components/labs/lab-reference-range-bar.tsx b/src/components/labs/lab-reference-range-bar.tsx
index 0fc0e1079..443855020 100644
--- a/src/components/labs/lab-reference-range-bar.tsx
+++ b/src/components/labs/lab-reference-range-bar.tsx
@@ -4,6 +4,7 @@ import { RangeBar } from "@/components/targets/range-bar";
 import { cn } from "@/lib/utils";
 
 import { useLabNumber } from "./use-lab-format";
+import { labUnitText, withLabUnit } from "@/lib/labs/dimensionless";
 
 /**
  * v1.37.34 — compact reference-range visualization for saved lab readings.
@@ -43,11 +44,14 @@ export function LabReferenceRangeBar({
   const scale = Math.max(Math.abs(referenceLow ?? referenceHigh!), 1);
   const min = referenceLow ?? referenceHigh! - scale;
   const max = referenceHigh ?? referenceLow! + scale;
-  const rangeLabel = !hasLow
-    ? `≤${labNumber(referenceHigh!)} ${unit}`
-    : !hasHigh
-      ? `≥${labNumber(referenceLow!)} ${unit}`
-      : `${labNumber(referenceLow!)}–${labNumber(referenceHigh!)} ${unit}`;
+  const rangeLabel = withLabUnit(
+    !hasLow
+      ? `≤${labNumber(referenceHigh!)}`
+      : !hasHigh
+        ? `≥${labNumber(referenceLow!)}`
+        : `${labNumber(referenceLow!)}–${labNumber(referenceHigh!)}`,
+    unit,
+  );
 
   return (
     <div
@@ -59,7 +63,7 @@ export function LabReferenceRangeBar({
         value={value}
         min={min}
         max={max}
-        unit={unit}
+        unit={labUnitText(unit)}
         compact
         tone="lab"
         formatValue={labNumber}
diff --git a/src/components/labs/lab-trend-card.tsx b/src/components/labs/lab-trend-card.tsx
index 94f87a107..c44e01897 100644
--- a/src/components/labs/lab-trend-card.tsx
+++ b/src/components/labs/lab-trend-card.tsx
@@ -7,6 +7,7 @@ import { TileHeader } from "@/components/insights/tile-header";
 import { useFormatters, useTranslations } from "@/lib/i18n/context";
 
 import type { BiomarkerTrendDto } from "./types";
+import { labUnitText } from "@/lib/labs/dimensionless";
 
 /**
  * v1.44 — the marker's slope over all its readings, and where that straight
@@ -35,12 +36,19 @@ export function LabTrendCard({
       : trend.slopePerYear < 0
         ? "falling"
         : "flat";
-  const slopeLine = t(`labs.trend.slope.${direction}`, {
-    amount: per(trend.slopePerYear),
-    unit,
-    n: trend.n,
-    since: fmt.dateShortSmartCalendar(trend.firstAt),
-  });
+  const shownUnit = labUnitText(unit);
+  // A value without a unit leaves the {unit} slot empty; close the gap it
+  // leaves rather than print a space before the full stop.
+  const tidy = (text: string) =>
+    shownUnit ? text : text.replace(/ +([.,])/g, "$1").replace(/ {2,}/g, " ");
+  const slopeLine = tidy(
+    t(`labs.trend.slope.${direction}`, {
+      amount: per(trend.slopePerYear),
+      unit: shownUnit,
+      n: trend.n,
+      since: fmt.dateShortSmartCalendar(trend.firstAt),
+    }),
+  );
   const projectionLine =
     trend.projection === "exits" && trend.exitDate
       ? t(`labs.trend.projection.exits.${trend.exitBound ?? "high"}`, {
@@ -85,11 +93,13 @@ export function LabTrendCard({
           </p>
         ) : null}
         <p className="text-muted-foreground text-xs">
-          {t("labs.trend.interval", {
-            lo: fmt.number(trend.slopeCi95[0], 2),
-            hi: fmt.number(trend.slopeCi95[1], 2),
-            unit,
-          })}
+          {tidy(
+            t("labs.trend.interval", {
+              lo: fmt.number(trend.slopeCi95[0], 2),
+              hi: fmt.number(trend.slopeCi95[1], 2),
+              unit: shownUnit,
+            }),
+          )}
         </p>
       </CardContent>
     </Card>
diff --git a/src/components/labs/labs-settings.tsx b/src/components/labs/labs-settings.tsx
index 12ca02e37..709f550b5 100644
--- a/src/components/labs/labs-settings.tsx
+++ b/src/components/labs/labs-settings.tsx
@@ -46,6 +46,7 @@ import {
 import { BiomarkerManager } from "./biomarker-manager";
 import type { BiomarkerDto, BiomarkerListResponse } from "./types";
 import { useLabsLocalOcr, useUpdateLabsLocalOcr } from "./use-ocr-extract";
+import { labUnitLabel } from "@/lib/labs/dimensionless";
 
 export function LabsSettings() {
   const { t } = useTranslations();
@@ -61,7 +62,7 @@ export function LabsSettings() {
   const reorderItems: ReorderItem[] = ordered.map((m) => ({
     id: m.id,
     name: m.name,
-    secondary: m.panel ? `${m.unit} · ${m.panel}` : m.unit,
+    secondary: [labUnitLabel(m.unit, t), m.panel].filter(Boolean).join(" · "),
   }));
 
   const manual = prefs.sortDir === "manual";
diff --git a/src/components/labs/marker-match-field.tsx b/src/components/labs/marker-match-field.tsx
index 399bdac2a..cd1521bd0 100644
--- a/src/components/labs/marker-match-field.tsx
+++ b/src/components/labs/marker-match-field.tsx
@@ -21,6 +21,7 @@ import { Badge } from "@/components/ui/badge";
 import { Label } from "@/components/ui/label";
 import { NativeSelect } from "@/components/ui/native-select";
 import { useTranslations } from "@/lib/i18n/context";
+import { labUnitLabel } from "@/lib/labs/dimensionless";
 
 export interface MarkerSuggestionDto {
   biomarkerId: string;
@@ -110,7 +111,7 @@ export function MarkerMatchField({
           <option key={suggestion.biomarkerId} value={suggestion.biomarkerId}>
             {t("labs.match.suggestionOption", {
               name: suggestion.name,
-              unit: suggestion.unit,
+              unit: labUnitLabel(suggestion.unit, t),
             })}
           </option>
         ))}
diff --git a/src/components/labs/source-range-note.tsx b/src/components/labs/source-range-note.tsx
index d5e3dde2c..b5a7f195e 100644
--- a/src/components/labs/source-range-note.tsx
+++ b/src/components/labs/source-range-note.tsx
@@ -5,6 +5,7 @@ import { useTranslations } from "@/lib/i18n/context";
 
 import type { LabResultDto } from "./types";
 import { useLabNumber } from "./use-lab-format";
+import { withLabUnit } from "@/lib/labs/dimensionless";
 
 /**
  * The reference window a reading's own report printed, shown wherever that
@@ -54,11 +55,14 @@ export function SourceRangeNote({
   // then stated from the converted bounds, in the marker's unit.
   const inForce =
     reading.sourceReferenceText ??
-    `${formatReferenceRange(
-      reading.referenceLow,
-      reading.referenceHigh,
-      labNumber,
-    )} ${reading.unit}`.trim();
+    withLabUnit(
+      formatReferenceRange(
+        reading.referenceLow,
+        reading.referenceHigh,
+        labNumber,
+      ),
+      reading.unit,
+    );
 
   const catalog = formatReferenceRange(
     reading.catalogReferenceLow,
@@ -77,7 +81,7 @@ export function SourceRangeNote({
         : null}
       {reading.referenceDivergesFromCatalog && catalog
         ? ` · ${t("labs.sourceRange.catalogDiffers", {
-            range: `${catalog} ${reading.unit}`.trim(),
+            range: withLabUnit(catalog, reading.unit),
           })}`
         : null}
     </span>
diff --git a/src/components/timeline/lab-lines.tsx b/src/components/timeline/lab-lines.tsx
index 619f627bc..833a4a7bc 100644
--- a/src/components/timeline/lab-lines.tsx
+++ b/src/components/timeline/lab-lines.tsx
@@ -38,6 +38,7 @@ import {
   formatDayMonthYear,
 } from "./timeline-dates";
 import { seriesNameLines, type TimelineLayout } from "./timeline-geometry";
+import { withLabUnit } from "@/lib/labs/dimensionless";
 
 /** "18 ng/mL", every digit the reading holds, in the reader's locale. */
 export type LabValueText = (
@@ -50,7 +51,7 @@ export function useLabValueText(): LabValueText {
   const labNumber = useLabNumber();
   return useCallback(
     (value, sourceValue, unit) =>
-      `${labNumber(value, sourceValue)} ${unit}`.trim(),
+      withLabUnit(labNumber(value, sourceValue), unit),
     [labNumber],
   );
 }
@@ -84,7 +85,7 @@ export function useLabReference(): (
         (v) => labNumber(v),
       );
       return range
-        ? t("timeline.labs.reference", { range: `${range} ${unit}`.trim() })
+        ? t("timeline.labs.reference", { range: withLabUnit(range, unit) })
         : null;
     },
     [t, labNumber],
diff --git a/src/lib/ai/coach/labs-snapshot.ts b/src/lib/ai/coach/labs-snapshot.ts
index 85e102617..5407b90aa 100644
--- a/src/lib/ai/coach/labs-snapshot.ts
+++ b/src/lib/ai/coach/labs-snapshot.ts
@@ -67,6 +67,7 @@ import { resolveLabFields } from "@/lib/labs/serialise";
 import { sanitizeForPrompt } from "@/lib/insights/sanitize";
 import { prisma } from "@/lib/db";
 import { isModuleEnabled } from "@/lib/modules/gate";
+import { labUnitText } from "@/lib/labs/dimensionless";
 
 /** Cap on distinct biomarkers in the block (newest reading first). */
 const MAX_BIOMARKERS = 24;
@@ -120,7 +121,7 @@ export interface CoachLabReading {
   value: number | null;
   /** Qualitative result text ("negativ" / …); null for a numeric row. */
   valueText: string | null;
-  /** Resolved unit; empty for a qualitative marker. */
+  /** Resolved unit; empty for a qualitative marker and for a ratio. */
   unit: string;
   referenceLow: number | null;
   referenceHigh: number | null;
@@ -359,7 +360,9 @@ export async function buildLabsSnapshotBlock(
           : null,
         value: row.value,
         valueText: row.valueText ? sanitizeValueText(row.valueText) : null,
-        unit: sanitizeForPrompt(resolved.unit, MAX_UNIT_CHARS),
+        // A value without a unit is stored as "1"; the model is shown none,
+        // so it never writes "3.6 1".
+        unit: sanitizeForPrompt(labUnitText(resolved.unit), MAX_UNIT_CHARS),
         referenceLow: resolved.referenceLow,
         referenceHigh: resolved.referenceHigh,
         // A qualitative row has nothing to compare against the bounds →
diff --git a/src/lib/day/records.ts b/src/lib/day/records.ts
index 31be1a0bb..ec2073c8e 100644
--- a/src/lib/day/records.ts
+++ b/src/lib/day/records.ts
@@ -47,6 +47,7 @@ import {
   readWorkoutsAroundRange,
   WORKOUT_PICK_SELECT,
 } from "@/lib/workouts/canonical-read";
+import { labUnitText } from "@/lib/labs/dimensionless";
 
 /** Everything a section reader needs about the day. */
 export interface DayFrame {
@@ -717,10 +718,9 @@ async function labsPart(frame: DayFrame): Promise<SectionPart> {
         title: row.analyte,
         meta:
           row.value !== null
-            ? // Every recorded digit, without the float noise a converted
-              // reading carries (the labs page prints the same figure).
+            ? // Every recorded digit, minus a converted reading's float noise.
               // eslint-disable-next-line healthlog/no-unlocalised-decimal -- the day contract's meta is wire text; the lab figure keeps the notation it was stored in
-              `${formatRecordedNumber(row.value, (v, digits) => v.toFixed(digits), row.sourceValue)} ${row.unit}`.trim()
+              `${formatRecordedNumber(row.value, (v, digits) => v.toFixed(digits), row.sourceValue)} ${labUnitText(row.unit)}`.trim()
             : (row.valueText ?? null),
         note: openText(row.noteEncrypted, "lab note"),
         href: row.biomarkerId ? `/labs/${row.biomarkerId}` : "/labs",
diff --git a/src/lib/doctor-report-pdf/clinical-records-notes-section.ts b/src/lib/doctor-report-pdf/clinical-records-notes-section.ts
index 02538766d..294399161 100644
--- a/src/lib/doctor-report-pdf/clinical-records-notes-section.ts
+++ b/src/lib/doctor-report-pdf/clinical-records-notes-section.ts
@@ -16,6 +16,7 @@ import {
   type DoctorReportPdfCursorState,
   type DoctorReportPdfRenderContext,
 } from "./render-context";
+import { withLabUnit } from "@/lib/labs/dimensionless";
 
 export function buildClinicalRecordsNotesSection(
   context: DoctorReportPdfRenderContext,
@@ -109,7 +110,7 @@ export function buildClinicalRecordsNotesSection(
         lr.panel ? `${lr.analyte} (${lr.panel})` : lr.analyte,
         isQualitative
           ? (lr.valueText ?? "")
-          : `${labNum(lr.value as number, lr.sourceValue)} ${lr.unit}`.trim(),
+          : withLabUnit(labNum(lr.value as number, lr.sourceValue), lr.unit),
         isQualitative ? "—" : referenceCell(lr),
         isQualitative
           ? ""
@@ -166,10 +167,10 @@ export function buildClinicalRecordsNotesSection(
       y += 4;
       for (const lr of diverging) {
         doc.text(
-          `* ${lr.analyte}: ${t("doctorReport.labsCatalogRangeLabel")} ${rangeText(
-            lr.catalogReferenceLow,
-            lr.catalogReferenceHigh,
-          )} ${lr.unit}`.trim(),
+          `* ${lr.analyte}: ${t("doctorReport.labsCatalogRangeLabel")} ${withLabUnit(
+            rangeText(lr.catalogReferenceLow, lr.catalogReferenceHigh),
+            lr.unit,
+          )}`.trim(),
           margin,
           y,
         );
diff --git a/src/lib/insights/biomarker-status.ts b/src/lib/insights/biomarker-status.ts
index 75c4c7f8b..0306ccf37 100644
--- a/src/lib/insights/biomarker-status.ts
+++ b/src/lib/insights/biomarker-status.ts
@@ -53,6 +53,7 @@ import {
 import { annotate } from "@/lib/logging/context";
 import { userDayKey } from "@/lib/tz/resolver";
 import { sanitizeForPrompt } from "@/lib/insights/sanitize";
+import { labUnitText } from "@/lib/labs/dimensionless";
 
 export type BiomarkerStatusResult = {
   hasProvider: boolean;
@@ -321,7 +322,7 @@ function biomarkerSnapshot(args: {
   // position below, so both are scrubbed exactly like the coach
   // labs-snapshot scrubs the same fields.
   const safeMarkerName = sanitizeForPrompt(marker.name, 120);
-  const safeMarkerUnit = sanitizeForPrompt(marker.unit, 40);
+  const safeMarkerUnit = sanitizeForPrompt(labUnitText(marker.unit), 40);
 
   const snapshot = {
     locale,
diff --git a/src/lib/jobs/reaction-line-labs.ts b/src/lib/jobs/reaction-line-labs.ts
index 8d71e8a37..d164e0c5a 100644
--- a/src/lib/jobs/reaction-line-labs.ts
+++ b/src/lib/jobs/reaction-line-labs.ts
@@ -8,6 +8,7 @@
 import { fenceUserText } from "@/lib/ai/coach/data-fence";
 import { prisma } from "@/lib/db";
 import { isModuleEnabled } from "@/lib/modules/gate";
+import { labUnitText } from "@/lib/labs/dimensionless";
 
 /** Up to eight results of the panel, fenced; null when there is nothing to say. */
 export async function labsPanelEvidence(
@@ -33,7 +34,8 @@ export async function labsPanelEvidence(
         lab.value === null
           ? fenceUserText(lab.valueText ?? "not reported")
           : String(lab.value);
-      const unit = lab.unit ? ` ${fenceUserText(lab.unit)}` : "";
+      const shown = labUnitText(lab.unit);
+      const unit = shown ? ` ${fenceUserText(shown)}` : "";
       return `- Newly arrived lab result: ${fenceUserText(lab.analyte)} ${value}${unit}.`;
     })
     .join("\n");
diff --git a/src/lib/mcp/doctor-visit-summary.ts b/src/lib/mcp/doctor-visit-summary.ts
index 6b00444d6..41c3aaaf1 100644
--- a/src/lib/mcp/doctor-visit-summary.ts
+++ b/src/lib/mcp/doctor-visit-summary.ts
@@ -19,6 +19,7 @@
 import type { DoctorReportData } from "@/lib/doctor-report-data";
 import { getMetricStatusMeta } from "@/lib/insights/metric-status-registry";
 import { fenceUserText } from "@/lib/ai/coach/data-fence";
+import { labUnitText } from "@/lib/labs/dimensionless";
 
 /**
  * Fallback units for the headline specialised metric types the generic
@@ -91,7 +92,7 @@ export function summariseForVisit(
     panel: l.panel,
     value: l.value,
     valueText: l.valueText,
-    unit: l.unit,
+    unit: labUnitText(l.unit),
     referenceLow: l.referenceLow,
     referenceHigh: l.referenceHigh,
     takenAt: l.takenAt,
diff --git a/src/lib/mcp/prompts.ts b/src/lib/mcp/prompts.ts
index 9507775c2..cdba743fd 100644
--- a/src/lib/mcp/prompts.ts
+++ b/src/lib/mcp/prompts.ts
@@ -34,6 +34,7 @@ import { detectDerivedBriefingSignals } from "@/lib/insights/derived-briefing";
 import { buildBriefingIllnessCycleContext } from "@/lib/insights/illness-cycle-briefing";
 import { resolveUserTimezone } from "@/lib/tz/resolver";
 import type { McpAuthContext } from "./auth";
+import { labUnitText } from "@/lib/labs/dimensionless";
 
 const MS_PER_DAY = 24 * 60 * 60 * 1000;
 
@@ -254,7 +255,7 @@ async function collectLabTrajectories(
       const history = readings.slice(0, 12).map((r) => ({
         value: r.value,
         valueText: r.valueText,
-        unit: r.unit,
+        unit: labUnitText(r.unit),
         referenceLow: r.referenceLow,
         referenceHigh: r.referenceHigh,
         takenAt: r.takenAt.toISOString(),
@@ -263,7 +264,7 @@ async function collectLabTrajectories(
       return {
         analyte: latest.analyte,
         panel: latest.panel,
-        unit: latest.unit,
+        unit: labUnitText(latest.unit),
         readingsOnFile: readings.length,
         latest: history[0],
         history,
diff --git a/src/lib/mcp/tools/get-labs.ts b/src/lib/mcp/tools/get-labs.ts
index f9c3dec33..7c233a298 100644
--- a/src/lib/mcp/tools/get-labs.ts
+++ b/src/lib/mcp/tools/get-labs.ts
@@ -2,12 +2,17 @@ import { z } from "zod/v4";
 
 import { fenceUserText } from "@/lib/ai/coach/data-fence";
 import { resolveMarkerForRead } from "@/lib/labs/biomarker-resolve";
-import { getLabHistory, LAB_HISTORY_MAX_LIMIT } from "@/lib/mcp/rich-reads";
+import {
+  getLabHistory,
+  LAB_HISTORY_MAX_LIMIT,
+  type LabHistoryResult,
+} from "@/lib/mcp/rich-reads";
 import { decodeOffsetCursor } from "@/lib/mcp/pagination";
 import type { McpAuthContext } from "../auth";
 import { coachReadOutput } from "./output-shapes";
 import { runCoachTool, whenModuleOn } from "./shared";
 import { READ_ONLY_ANNOTATIONS, type McpToolDefinition } from "./types";
+import { labUnitText } from "@/lib/labs/dimensionless";
 
 /** Output schema for `get_labs` — latest-per-biomarker OR a paginated history. */
 const getLabsOutput: z.ZodRawShape = {
@@ -59,6 +64,19 @@ function fenceLabText(value: unknown): unknown {
   );
 }
 
+/**
+ * A value without a unit (a ratio, INR) is stored as the UCUM unity "1". The
+ * model is shown no unit for it, as the Coach's lab block does, so it never
+ * writes "3.6 1".
+ */
+function withShownUnits(result: LabHistoryResult): LabHistoryResult {
+  if (!result.readings) return result;
+  return {
+    ...result,
+    readings: result.readings.map((r) => ({ ...r, unit: labUnitText(r.unit) })),
+  };
+}
+
 /** `get_labs` behind its module gate: latest-per-biomarker or a history page. */
 function readLabs(
   ctx: McpAuthContext,
@@ -78,7 +96,7 @@ function readLabs(
       analyte,
       offset: decodeOffsetCursor(args.cursor),
       limit: LAB_HISTORY_MAX_LIMIT,
-    });
+    }).then(withShownUnits);
   }
   // Default: latest reading per biomarker via the Coach labs read. A name that
   // resolves to one of the user's markers (an alias or a catalog abbreviation
diff --git a/src/lib/mcp/tools/render/citation-text.ts b/src/lib/mcp/tools/render/citation-text.ts
index 9326d5f52..89059d6f1 100644
--- a/src/lib/mcp/tools/render/citation-text.ts
+++ b/src/lib/mcp/tools/render/citation-text.ts
@@ -6,6 +6,7 @@
 import { fenceUserText } from "@/lib/ai/coach/data-fence";
 import type { NutrientsDailyResult } from "@/lib/mcp/nutrients-read";
 import type { NutrientUpperLimit } from "@/lib/nutrients/catalog";
+import { labUnitText } from "@/lib/labs/dimensionless";
 
 /** Finite-number guard for the citation summarisers. */
 function num(v: unknown): number | null {
@@ -66,7 +67,9 @@ export function plainLabText(rid: string, result: unknown): string {
       : typeof reading.valueText === "string"
         ? reading.valueText
         : "—";
-  const unit = typeof reading.unit === "string" ? reading.unit : "";
+  // A value without a unit (a ratio, INR) is stored as "1"; it reads as none.
+  const unit =
+    typeof reading.unit === "string" ? labUnitText(reading.unit) : "";
   const status =
     typeof reading.rangeStatus === "string" ? reading.rangeStatus : "";
   const taken =