GIVE ME SMOOTS. Closes #87.

frontend/src/App.tsx

@@ -18,6 +18,7 @@ import {
 } from './hooks';
 import { AppShell } from './components/AppShell';
 import type { MessageInputHandle } from './components/MessageInput';
+import { DistanceUnitProvider } from './contexts/DistanceUnitContext';
 import { messageContainsMention } from './utils/messageParser';
 import { getStateKey } from './utils/conversationState';
 import type { Conversation, Message, RawPacket } from './types';
@@ -91,10 +92,12 @@ export function App() {
     showCracker,
     crackerRunning,
     localLabel,
+    distanceUnit,
     setSettingsSection,
     setSidebarOpen,
     setCrackerRunning,
     setLocalLabel,
+    setDistanceUnit,
     handleCloseSettingsView,
     handleToggleSettingsView,
     handleOpenNewMessage,
@@ -564,29 +567,31 @@ export function App() {
     setContactsLoaded,
   ]);
   return (
-    <AppShell
-      localLabel={localLabel}
-      showNewMessage={showNewMessage}
-      showSettings={showSettings}
-      settingsSection={settingsSection}
-      sidebarOpen={sidebarOpen}
-      showCracker={showCracker}
-      onSettingsSectionChange={setSettingsSection}
-      onSidebarOpenChange={setSidebarOpen}
-      onCrackerRunningChange={setCrackerRunning}
-      onToggleSettingsView={handleToggleSettingsView}
-      onCloseSettingsView={handleCloseSettingsView}
-      onCloseNewMessage={handleCloseNewMessage}
-      onLocalLabelChange={setLocalLabel}
-      statusProps={statusProps}
-      sidebarProps={sidebarProps}
-      conversationPaneProps={conversationPaneProps}
-      searchProps={searchProps}
-      settingsProps={settingsProps}
-      crackerProps={crackerProps}
-      newMessageModalProps={newMessageModalProps}
-      contactInfoPaneProps={contactInfoPaneProps}
-      channelInfoPaneProps={channelInfoPaneProps}
-    />
+    <DistanceUnitProvider distanceUnit={distanceUnit} setDistanceUnit={setDistanceUnit}>
+      <AppShell
+        localLabel={localLabel}
+        showNewMessage={showNewMessage}
+        showSettings={showSettings}
+        settingsSection={settingsSection}
+        sidebarOpen={sidebarOpen}
+        showCracker={showCracker}
+        onSettingsSectionChange={setSettingsSection}
+        onSidebarOpenChange={setSidebarOpen}
+        onCrackerRunningChange={setCrackerRunning}
+        onToggleSettingsView={handleToggleSettingsView}
+        onCloseSettingsView={handleCloseSettingsView}
+        onCloseNewMessage={handleCloseNewMessage}
+        onLocalLabelChange={setLocalLabel}
+        statusProps={statusProps}
+        sidebarProps={sidebarProps}
+        conversationPaneProps={conversationPaneProps}
+        searchProps={searchProps}
+        settingsProps={settingsProps}
+        crackerProps={crackerProps}
+        newMessageModalProps={newMessageModalProps}
+        contactInfoPaneProps={contactInfoPaneProps}
+        channelInfoPaneProps={channelInfoPaneProps}
+      />
+    </DistanceUnitProvider>
   );
 }

frontend/src/components/ContactInfoPane.tsx

@@ -24,6 +24,7 @@ import { handleKeyboardActivate } from '../utils/a11y';
 import { ContactAvatar } from './ContactAvatar';
 import { Sheet, SheetContent, SheetDescription, SheetHeader, SheetTitle } from './ui/sheet';
 import { toast } from './ui/sonner';
+import { useDistanceUnit } from '../contexts/DistanceUnitContext';
 import type {
   Contact,
   ContactActiveRoom,
@@ -82,6 +83,7 @@ export function ContactInfoPane({
   onToggleBlockedKey,
   onToggleBlockedName,
 }: ContactInfoPaneProps) {
+  const { distanceUnit } = useDistanceUnit();
   const isNameOnly = contactKey?.startsWith('name:') ?? false;
   const nameOnlyValue = isNameOnly && contactKey ? contactKey.slice(5) : null;
 
@@ -315,7 +317,7 @@ export function ContactInfoPane({
                   <InfoItem label="Last Contacted" value={formatTime(contact.last_contacted)} />
                 )}
                 {distFromUs !== null && (
-                  <InfoItem label="Distance" value={formatDistance(distFromUs)} />
+                  <InfoItem label="Distance" value={formatDistance(distFromUs, distanceUnit)} />
                 )}
                 {effectiveRoute && (
                   <InfoItem

frontend/src/components/ContactStatusInfo.tsx

@@ -11,6 +11,7 @@ import {
 import { getMapFocusHash } from '../utils/urlHash';
 import { handleKeyboardActivate } from '../utils/a11y';
 import type { Contact } from '../types';
+import { useDistanceUnit } from '../contexts/DistanceUnitContext';
 import { ContactRoutingOverrideModal } from './ContactRoutingOverrideModal';
 
 interface ContactStatusInfoProps {
@@ -24,6 +25,7 @@ interface ContactStatusInfoProps {
  * shared between ChatHeader and RepeaterDashboard.
  */
 export function ContactStatusInfo({ contact, ourLat, ourLon }: ContactStatusInfoProps) {
+  const { distanceUnit } = useDistanceUnit();
   const [routingModalOpen, setRoutingModalOpen] = useState(false);
   const parts: ReactNode[] = [];
   const effectiveRoute = getEffectiveContactRoute(contact);
@@ -74,7 +76,7 @@ export function ContactStatusInfo({ contact, ourLat, ourLon }: ContactStatusInfo
         >
           {contact.lat!.toFixed(3)}, {contact.lon!.toFixed(3)}
         </span>
-        {distFromUs !== null && ` (${formatDistance(distFromUs)})`}
+        {distFromUs !== null && ` (${formatDistance(distFromUs, distanceUnit)})`}
       </span>
     );
   }

frontend/src/components/PathModal.tsx

@@ -14,6 +14,8 @@ import {
 } from '../utils/pathUtils';
 import { formatTime } from '../utils/messageParser';
 import { getMapFocusHash } from '../utils/urlHash';
+import { useDistanceUnit } from '../contexts/DistanceUnitContext';
+import type { DistanceUnit } from '../utils/distanceUnits';
 
 const PathRouteMap = lazy(() =>
   import('./PathRouteMap').then((m) => ({ default: m.PathRouteMap }))
@@ -44,6 +46,7 @@ export function PathModal({
   isResendable,
   onResend,
 }: PathModalProps) {
+  const { distanceUnit } = useDistanceUnit();
   const [expandedMaps, setExpandedMaps] = useState<Set<number>>(new Set());
   const hasResendActions = isOutgoingChan && messageId !== undefined && onResend;
   const hasPaths = paths.length > 0;
@@ -120,7 +123,8 @@ export function PathModal({
                         resolvedPaths[0].resolved.sender.lon,
                         resolvedPaths[0].resolved.receiver.lat,
                         resolvedPaths[0].resolved.receiver.lon
-                      )!
+                      )!,
+                      distanceUnit
                     )}
                   </span>
                 </div>
@@ -171,7 +175,11 @@ export function PathModal({
                       </Suspense>
                     </div>
                   )}
-                  <PathVisualization resolved={pathData.resolved} senderInfo={senderInfo} />
+                  <PathVisualization
+                    resolved={pathData.resolved}
+                    senderInfo={senderInfo}
+                    distanceUnit={distanceUnit}
+                  />
                 </div>
               );
             })}
@@ -227,9 +235,10 @@ export function PathModal({
 interface PathVisualizationProps {
   resolved: ResolvedPath;
   senderInfo: SenderInfo;
+  distanceUnit: DistanceUnit;
 }
 
-function PathVisualization({ resolved, senderInfo }: PathVisualizationProps) {
+function PathVisualization({ resolved, senderInfo, distanceUnit }: PathVisualizationProps) {
   // Track previous location for each hop to calculate distances
   // Returns null if previous hop was ambiguous or has invalid location
   const getPrevLocation = (hopIndex: number): { lat: number | null; lon: number | null } | null => {
@@ -264,6 +273,7 @@ function PathVisualization({ resolved, senderInfo }: PathVisualizationProps) {
         name={resolved.sender.name}
         prefix={resolved.sender.prefix}
         distance={null}
+        distanceUnit={distanceUnit}
         isFirst
         lat={resolved.sender.lat}
         lon={resolved.sender.lon}
@@ -277,6 +287,7 @@ function PathVisualization({ resolved, senderInfo }: PathVisualizationProps) {
           hop={hop}
           hopNumber={index + 1}
           prevLocation={getPrevLocation(index)}
+          distanceUnit={distanceUnit}
         />
       ))}
 
@@ -286,6 +297,7 @@ function PathVisualization({ resolved, senderInfo }: PathVisualizationProps) {
         name={resolved.receiver.name}
         prefix={resolved.receiver.prefix}
         distance={calculateReceiverDistance(resolved)}
+        distanceUnit={distanceUnit}
         isLast
         lat={resolved.receiver.lat}
         lon={resolved.receiver.lon}
@@ -300,7 +312,7 @@ function PathVisualization({ resolved, senderInfo }: PathVisualizationProps) {
           </span>
           <span className="text-sm font-medium">
             {resolved.hasGaps ? '>' : ''}
-            {formatDistance(resolved.totalDistances[0])}
+            {formatDistance(resolved.totalDistances[0], distanceUnit)}
           </span>
         </div>
       )}
@@ -313,6 +325,7 @@ interface PathNodeProps {
   name: string;
   prefix: string;
   distance: number | null;
+  distanceUnit: DistanceUnit;
   isFirst?: boolean;
   isLast?: boolean;
   /** Optional coordinates for map link */
@@ -327,6 +340,7 @@ function PathNode({
   name,
   prefix,
   distance,
+  distanceUnit,
   isFirst,
   isLast,
   lat,
@@ -353,7 +367,9 @@ function PathNode({
         <div className="font-medium truncate">
           {name}
           {distance !== null && (
-            <span className="text-xs text-muted-foreground ml-1">- {formatDistance(distance)}</span>
+            <span className="text-xs text-muted-foreground ml-1">
+              - {formatDistance(distance, distanceUnit)}
+            </span>
           )}
           {hasLocation && <CoordinateLink lat={lat!} lon={lon!} publicKey={publicKey!} />}
         </div>
@@ -366,9 +382,10 @@ interface HopNodeProps {
   hop: PathHop;
   hopNumber: number;
   prevLocation: { lat: number | null; lon: number | null } | null;
+  distanceUnit: DistanceUnit;
 }
 
-function HopNode({ hop, hopNumber, prevLocation }: HopNodeProps) {
+function HopNode({ hop, hopNumber, prevLocation, distanceUnit }: HopNodeProps) {
   const isAmbiguous = hop.matches.length > 1;
   const isUnknown = hop.matches.length === 0;
 
@@ -417,7 +434,7 @@ function HopNode({ hop, hopNumber, prevLocation }: HopNodeProps) {
                   {contact.name || contact.public_key.slice(0, 12)}
                   {dist !== null && (
                     <span className="text-xs text-muted-foreground ml-1">
-                      - {formatDistance(dist)}
+                      - {formatDistance(dist, distanceUnit)}
                     </span>
                   )}
                   {hasLocation && (
@@ -436,7 +453,7 @@ function HopNode({ hop, hopNumber, prevLocation }: HopNodeProps) {
             {hop.matches[0].name || hop.matches[0].public_key.slice(0, 12)}
             {hop.distanceFromPrev !== null && (
               <span className="text-xs text-muted-foreground ml-1">
-                - {formatDistance(hop.distanceFromPrev)}
+                - {formatDistance(hop.distanceFromPrev, distanceUnit)}
               </span>
             )}
             {isValidLocation(hop.matches[0].lat, hop.matches[0].lon) && (

frontend/src/components/repeater/RepeaterNeighborsPane.tsx

@@ -2,6 +2,7 @@ import { useMemo, lazy, Suspense } from 'react';
 import { cn } from '@/lib/utils';
 import { RepeaterPane, NotFetched, formatDuration } from './repeaterPaneShared';
 import { isValidLocation, calculateDistance, formatDistance } from '../../utils/pathUtils';
+import { useDistanceUnit } from '../../contexts/DistanceUnitContext';
 import type {
   Contact,
   RepeaterNeighborsResponse,
@@ -35,6 +36,7 @@ export function NeighborsPane({
   nodeInfoState: PaneState;
   repeaterName: string | null;
 }) {
+  const { distanceUnit } = useDistanceUnit();
   const advertLat = repeaterContact?.lat ?? null;
   const advertLon = repeaterContact?.lon ?? null;
 
@@ -93,7 +95,7 @@ export function NeighborsPane({
       if (hasValidRepeaterGps && isValidLocation(nLat, nLon)) {
         const distKm = calculateDistance(positionSource.lat, positionSource.lon, nLat, nLon);
         if (distKm != null) {
-          dist = formatDistance(distKm);
+          dist = formatDistance(distKm, distanceUnit);
           anyDist = true;
         }
       }
@@ -111,7 +113,7 @@ export function NeighborsPane({
       sorted: enriched,
       hasDistances: anyDist,
     };
-  }, [contacts, data, hasValidRepeaterGps, positionSource.lat, positionSource.lon]);
+  }, [contacts, data, distanceUnit, hasValidRepeaterGps, positionSource.lat, positionSource.lon]);
 
   return (
     <RepeaterPane

frontend/src/components/settings/SettingsLocalSection.tsx

@@ -11,6 +11,12 @@ import {
 } from '../../utils/lastViewedConversation';
 import { ThemeSelector } from './ThemeSelector';
 import { getLocalLabel, setLocalLabel, type LocalLabel } from '../../utils/localLabel';
+import {
+  DISTANCE_UNIT_LABELS,
+  DISTANCE_UNITS,
+  setSavedDistanceUnit,
+} from '../../utils/distanceUnits';
+import { useDistanceUnit } from '../../contexts/DistanceUnitContext';
 
 export function SettingsLocalSection({
   onLocalLabelChange,
@@ -19,6 +25,7 @@ export function SettingsLocalSection({
   onLocalLabelChange?: (label: LocalLabel) => void;
   className?: string;
 }) {
+  const { distanceUnit, setDistanceUnit } = useDistanceUnit();
   const [reopenLastConversation, setReopenLastConversation] = useState(
     getReopenLastConversationEnabled
   );
@@ -82,6 +89,31 @@ export function SettingsLocalSection({
 
       <Separator />
 
+      <div className="space-y-3">
+        <Label htmlFor="distance-units">Distance Units</Label>
+        <select
+          id="distance-units"
+          value={distanceUnit}
+          onChange={(event) => {
+            const nextUnit = event.target.value as (typeof DISTANCE_UNITS)[number];
+            setSavedDistanceUnit(nextUnit);
+            setDistanceUnit(nextUnit);
+          }}
+          className="w-full rounded-md border border-input bg-background px-3 py-2 text-sm"
+        >
+          {DISTANCE_UNITS.map((unit) => (
+            <option key={unit} value={unit}>
+              {DISTANCE_UNIT_LABELS[unit]}
+            </option>
+          ))}
+        </select>
+        <p className="text-xs text-muted-foreground">
+          Controls how distances are shown throughout the app.
+        </p>
+      </div>
+
+      <Separator />
+
       <label className="flex items-center gap-3 cursor-pointer">
         <input
           type="checkbox"

frontend/src/contexts/DistanceUnitContext.tsx

@@ -0,0 +1,31 @@
+import { createContext, useContext, type ReactNode } from 'react';
+
+import type { DistanceUnit } from '../utils/distanceUnits';
+
+interface DistanceUnitContextValue {
+  distanceUnit: DistanceUnit;
+  setDistanceUnit: (unit: DistanceUnit) => void;
+}
+
+const noop = () => {};
+
+const DistanceUnitContext = createContext<DistanceUnitContextValue>({
+  distanceUnit: 'imperial',
+  setDistanceUnit: noop,
+});
+
+export function DistanceUnitProvider({
+  distanceUnit,
+  setDistanceUnit,
+  children,
+}: DistanceUnitContextValue & { children: ReactNode }) {
+  return (
+    <DistanceUnitContext.Provider value={{ distanceUnit, setDistanceUnit }}>
+      {children}
+    </DistanceUnitContext.Provider>
+  );
+}
+
+export function useDistanceUnit() {
+  return useContext(DistanceUnitContext);
+}

frontend/src/hooks/useAppShell.ts

@@ -1,6 +1,7 @@
 import { startTransition, useCallback, useEffect, useRef, useState } from 'react';
 
 import { getLocalLabel, type LocalLabel } from '../utils/localLabel';
+import { getSavedDistanceUnit, type DistanceUnit } from '../utils/distanceUnits';
 import type { SettingsSection } from '../components/settings/settingsConstants';
 import { parseHashSettingsSection, updateSettingsHash } from '../utils/urlHash';
 
@@ -12,10 +13,12 @@ interface UseAppShellResult {
   showCracker: boolean;
   crackerRunning: boolean;
   localLabel: LocalLabel;
+  distanceUnit: DistanceUnit;
   setSettingsSection: (section: SettingsSection) => void;
   setSidebarOpen: (open: boolean) => void;
   setCrackerRunning: (running: boolean) => void;
   setLocalLabel: (label: LocalLabel) => void;
+  setDistanceUnit: (unit: DistanceUnit) => void;
   handleCloseSettingsView: () => void;
   handleToggleSettingsView: () => void;
   handleOpenNewMessage: () => void;
@@ -34,6 +37,7 @@ export function useAppShell(): UseAppShellResult {
   const [showCracker, setShowCracker] = useState(false);
   const [crackerRunning, setCrackerRunning] = useState(false);
   const [localLabel, setLocalLabel] = useState(getLocalLabel);
+  const [distanceUnit, setDistanceUnit] = useState(getSavedDistanceUnit);
   const previousHashRef = useRef('');
 
   useEffect(() => {
@@ -87,10 +91,12 @@ export function useAppShell(): UseAppShellResult {
     showCracker,
     crackerRunning,
     localLabel,
+    distanceUnit,
     setSettingsSection,
     setSidebarOpen,
     setCrackerRunning,
     setLocalLabel,
+    setDistanceUnit,
     handleCloseSettingsView,
     handleToggleSettingsView,
     handleOpenNewMessage,

frontend/src/test/distanceUnits.test.ts

@@ -0,0 +1,32 @@
+import { beforeEach, describe, expect, it } from 'vitest';
+
+import {
+  DISTANCE_UNIT_KEY,
+  getSavedDistanceUnit,
+  setSavedDistanceUnit,
+} from '../utils/distanceUnits';
+
+describe('distanceUnits utilities', () => {
+  beforeEach(() => {
+    localStorage.clear();
+  });
+
+  it('defaults to imperial when unset', () => {
+    expect(getSavedDistanceUnit()).toBe('imperial');
+  });
+
+  it('returns the stored unit when valid', () => {
+    localStorage.setItem(DISTANCE_UNIT_KEY, 'metric');
+    expect(getSavedDistanceUnit()).toBe('metric');
+  });
+
+  it('falls back to imperial for invalid stored values', () => {
+    localStorage.setItem(DISTANCE_UNIT_KEY, 'parsecs');
+    expect(getSavedDistanceUnit()).toBe('imperial');
+  });
+
+  it('stores the selected distance unit', () => {
+    setSavedDistanceUnit('smoots');
+    expect(localStorage.getItem(DISTANCE_UNIT_KEY)).toBe('smoots');
+  });
+});

frontend/src/test/pathUtils.test.ts

@@ -685,22 +685,39 @@ describe('isValidLocation', () => {
 });
 
 describe('formatDistance', () => {
-  it('formats distances under 1km in meters', () => {
-    expect(formatDistance(0.5)).toBe('500m');
-    expect(formatDistance(0.123)).toBe('123m');
-    expect(formatDistance(0.9999)).toBe('1000m');
+  const formatInteger = (value: number) => value.toLocaleString();
+  const formatOneDecimal = (value: number) =>
+    value.toLocaleString(undefined, {
+      minimumFractionDigits: 1,
+      maximumFractionDigits: 1,
+    });
+
+  it('defaults to imperial formatting', () => {
+    expect(formatDistance(0.01)).toBe(`${formatInteger(33)}ft`);
+    expect(formatDistance(0.5)).toBe(`${formatOneDecimal(0.5 * 0.621371)}mi`);
+    expect(formatDistance(1)).toBe(`${formatOneDecimal(0.621371)}mi`);
   });
 
-  it('formats distances at or above 1km with one decimal', () => {
-    expect(formatDistance(1)).toBe('1.0km');
-    expect(formatDistance(1.5)).toBe('1.5km');
-    expect(formatDistance(12.34)).toBe('12.3km');
-    expect(formatDistance(100)).toBe('100.0km');
+  it('formats metric distances in meters and kilometers', () => {
+    expect(formatDistance(0.5, 'metric')).toBe(`${formatInteger(500)}m`);
+    expect(formatDistance(0.123, 'metric')).toBe(`${formatInteger(123)}m`);
+    expect(formatDistance(0.9999, 'metric')).toBe(`${formatInteger(1000)}m`);
+    expect(formatDistance(1, 'metric')).toBe(`${formatOneDecimal(1)}km`);
+    expect(formatDistance(12.34, 'metric')).toBe(`${formatOneDecimal(12.34)}km`);
   });
 
-  it('rounds meters to nearest integer', () => {
-    expect(formatDistance(0.4567)).toBe('457m');
-    expect(formatDistance(0.001)).toBe('1m');
+  it('formats smoot distances using 1.7018 meters per smoot', () => {
+    expect(formatDistance(0.0017018, 'smoots')).toBe(`${formatOneDecimal(1)} smoot`);
+    expect(formatDistance(0.001, 'smoots')).toBe(`${formatOneDecimal(0.6)} smoots`);
+    expect(formatDistance(1, 'smoots')).toBe(`${formatInteger(588)} smoots`);
+  });
+
+  it('applies locale separators to large values', () => {
+    expect(formatDistance(1.234, 'metric')).toBe(`${formatOneDecimal(1.234)}km`);
+    expect(formatDistance(1234, 'metric')).toBe(`${formatOneDecimal(1234)}km`);
+    expect(formatDistance(2.1, 'smoots')).toContain(
+      formatInteger(Math.round((2.1 * 1000) / 1.7018))
+    );
   });
 });
 

frontend/src/test/settingsModal.test.tsx

@@ -19,6 +19,7 @@ import {
   REOPEN_LAST_CONVERSATION_KEY,
 } from '../utils/lastViewedConversation';
 import { api } from '../api';
+import { DISTANCE_UNIT_KEY } from '../utils/distanceUnits';
 
 const baseConfig: RadioConfig = {
   public_key: 'aa'.repeat(32),
@@ -509,6 +510,18 @@ describe('SettingsModal', () => {
     expect(localStorage.getItem(LAST_VIEWED_CONVERSATION_KEY)).toBeNull();
   });
 
+  it('defaults distance units to imperial and stores local changes', () => {
+    renderModal();
+    openLocalSection();
+
+    const select = screen.getByLabelText('Distance Units');
+    expect(select).toHaveValue('imperial');
+
+    fireEvent.change(select, { target: { value: 'smoots' } });
+
+    expect(localStorage.getItem(DISTANCE_UNIT_KEY)).toBe('smoots');
+  });
+
   it('purges decrypted raw packets via maintenance endpoint action', async () => {
     const runMaintenanceSpy = vi.spyOn(api, 'runMaintenance').mockResolvedValue({
       packets_deleted: 12,

frontend/src/utils/distanceUnits.ts

@@ -0,0 +1,32 @@
+export const DISTANCE_UNIT_KEY = 'remoteterm-distance-unit';
+
+export const DISTANCE_UNITS = ['imperial', 'metric', 'smoots'] as const;
+
+export type DistanceUnit = (typeof DISTANCE_UNITS)[number];
+
+export const DISTANCE_UNIT_LABELS: Record<DistanceUnit, string> = {
+  imperial: 'Imperial',
+  metric: 'Metric',
+  smoots: 'Smoots',
+};
+
+function isDistanceUnit(value: unknown): value is DistanceUnit {
+  return typeof value === 'string' && DISTANCE_UNITS.includes(value as DistanceUnit);
+}
+
+export function getSavedDistanceUnit(): DistanceUnit {
+  try {
+    const raw = localStorage.getItem(DISTANCE_UNIT_KEY);
+    return isDistanceUnit(raw) ? raw : 'imperial';
+  } catch {
+    return 'imperial';
+  }
+}
+
+export function setSavedDistanceUnit(unit: DistanceUnit): void {
+  try {
+    localStorage.setItem(DISTANCE_UNIT_KEY, unit);
+  } catch {
+    // localStorage may be unavailable
+  }
+}

frontend/src/utils/pathUtils.ts

@@ -1,4 +1,5 @@
 import type { Contact, ContactRoute, RadioConfig, MessagePath } from '../types';
+import type { DistanceUnit } from './distanceUnits';
 import { CONTACT_TYPE_REPEATER } from '../types';
 
 const MAX_PATH_BYTES = 64;
@@ -343,13 +344,35 @@ export function isValidLocation(lat: number | null, lon: number | null): boolean
 }
 
 /**
- * Format distance in human-readable form (m or km)
+ * Format distance in human-readable form using the selected display unit.
  */
-export function formatDistance(km: number): string {
-  if (km < 1) {
-    return `${Math.round(km * 1000)}m`;
+export function formatDistance(km: number, unit: DistanceUnit = 'imperial'): string {
+  const formatInteger = (value: number) => value.toLocaleString();
+  const formatOneDecimal = (value: number) =>
+    value.toLocaleString(undefined, {
+      minimumFractionDigits: 1,
+      maximumFractionDigits: 1,
+    });
+
+  if (unit === 'metric') {
+    if (km < 1) {
+      return `${formatInteger(Math.round(km * 1000))}m`;
+    }
+    return `${formatOneDecimal(km)}km`;
   }
-  return `${km.toFixed(1)}km`;
+
+  if (unit === 'smoots') {
+    const smoots = (km * 1000) / 1.7018;
+    const rounded = smoots < 10 ? Number(smoots.toFixed(1)) : Math.round(smoots);
+    const display = smoots < 10 ? formatOneDecimal(rounded) : formatInteger(rounded);
+    return `${display} ${rounded === 1 ? 'smoot' : 'smoots'}`;
+  }
+
+  const miles = km * 0.621371;
+  if (miles < 0.1) {
+    return `${formatInteger(Math.round(km * 3280.839895))}ft`;
+  }
+  return `${formatOneDecimal(miles)}mi`;
 }
 
 /**