diff --git a/locales/rn/de.json b/locales/rn/de.json
index 9cce5e08..7ea5fb1f 100644
--- a/locales/rn/de.json
+++ b/locales/rn/de.json
@@ -76,6 +76,7 @@
       "clear_confirm": "Alle entfernen",
       "clear_description": "Alle Termine in diesem Kalender werden gelöscht. Termine, die auch zu einem anderen Kalender gehören, werden nur aus diesem entfernt.",
       "clear_title": "Alle Termine entfernen?",
+      "color_invalid": "Geben Sie eine Farbe als sechs Hex-Ziffern ein, mit oder ohne #, etwa #3b82f6.",
       "delete_description": "Der Kalender und alle seine Termine werden gelöscht. Dies kann nicht rückgängig gemacht werden.",
       "delete_title": "Kalender löschen?",
       "description_field": "Beschreibung",
diff --git a/locales/rn/en.json b/locales/rn/en.json
index a819ca55..04385b69 100644
--- a/locales/rn/en.json
+++ b/locales/rn/en.json
@@ -95,7 +95,7 @@
       "clear_confirm": "Remove all",
       "clear_description": "Every event in this calendar will be deleted. Events that also belong to another calendar are only unlinked.",
       "clear_title": "Remove all events?",
-      "color_invalid": "Enter a color as # and six hex digits, such as #3b82f6.",
+      "color_invalid": "Enter a color as six hex digits, with or without #, such as #3b82f6.",
       "custom_color": "Custom color (hex)",
       "delete_description": "The calendar and all of its events will be deleted. This cannot be undone.",
       "delete_title": "Delete calendar?",
diff --git a/src/components/calendar/CalendarEditSheet.tsx b/src/components/calendar/CalendarEditSheet.tsx
index 2c1fcf94..739aebc0 100644
--- a/src/components/calendar/CalendarEditSheet.tsx
+++ b/src/components/calendar/CalendarEditSheet.tsx
@@ -27,7 +27,7 @@ import { radius, spacing, typography, type ThemePalette } from '../../theme/toke
 import { useColors } from '../../theme/colors';
 import { useLocaleStore, type TranslateFn } from '../../stores/locale-store';
 import { CALENDAR_COLOR_PALETTE, calendarColorName, getCalendarColor } from '../../lib/calendar-utils';
-import { customColorGrid, normalizeHexColor } from '../../lib/calendar-custom-color';
+import { customColorGrid, HEX_FIELD_MAX_LENGTH, hexFieldText, normalizeHexColor } from '../../lib/calendar-custom-color';
 
 const CUSTOM_COLOR_GRID = customColorGrid();
 import Button from '../Button';
@@ -260,11 +260,14 @@ export function CalendarEditSheet({ visible, calendar, onSave, onClose }: Calend
                       const hex = normalizeHexColor(v);
                       if (hex) setColor(hex);
                     }}
+                    // "3b82f6" works as well as "#3b82f6"; leaving the field
+                    // shows it with its "#".
+                    onBlur={() => setHexInput((v) => hexFieldText(v))}
                     placeholder="#3b82f6"
                     placeholderTextColor={c.textMuted}
                     autoCapitalize="none"
                     autoCorrect={false}
-                    maxLength={7}
+                    maxLength={HEX_FIELD_MAX_LENGTH}
                     accessibilityLabel={t('calendar.management.custom_color', 'Custom color (hex)')}
                     style={[styles.input, styles.hexInput, hexInvalid && styles.inputInvalid]}
                   />
@@ -283,7 +286,7 @@ export function CalendarEditSheet({ visible, calendar, onSave, onClose }: Calend
                 </View>
                 {hexInvalid && (
                   <Text style={styles.error}>
-                    {t('calendar.management.color_invalid', 'Enter a color as # and six hex digits, such as #3b82f6.')}
+                    {t('calendar.management.color_invalid', 'Enter a color as six hex digits, with or without #, such as #3b82f6.')}
                   </Text>
                 )}
                 {moreColors && (
diff --git a/src/lib/__tests__/calendar-custom-color.test.ts b/src/lib/__tests__/calendar-custom-color.test.ts
index e8f534bb..0a41bbba 100644
--- a/src/lib/__tests__/calendar-custom-color.test.ts
+++ b/src/lib/__tests__/calendar-custom-color.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest';
-import { customColorGrid, normalizeHexColor } from '../calendar-custom-color';
+import { customColorGrid, HEX_FIELD_MAX_LENGTH, hexFieldText, normalizeHexColor } from '../calendar-custom-color';
 
 describe('normalizeHexColor', () => {
   it('takes a typed hex colour in its usual spellings', () => {
@@ -23,3 +23,31 @@ describe('customColorGrid', () => {
     expect(grid[1][0]).toBe('#c32222');
   });
 });
+
+describe('the hex field', () => {
+  it('shows a colour typed without "#" with it once the user leaves the field', () => {
+    expect(hexFieldText('3b82f6')).toBe('#3b82f6');
+    expect(hexFieldText('3B82F6')).toBe('#3b82f6');
+    expect(hexFieldText('#3b82f6')).toBe('#3b82f6');
+    expect(hexFieldText('3b8')).toBe('#33bb88');
+    // Not a colour: left as typed for the hint under the field.
+    expect(hexFieldText('3b82f')).toBe('3b82f');
+  });
+
+  it('takes a pasted colour with spaces around it', () => {
+    const pasted = ' #3b82f6 ';
+    expect(pasted.length).toBeLessThanOrEqual(HEX_FIELD_MAX_LENGTH);
+    expect(normalizeHexColor(pasted.slice(0, HEX_FIELD_MAX_LENGTH))).toBe('#3b82f6');
+  });
+});
+
+describe('the calendar sheet’s hex field', () => {
+  it('spells the colour out on blur and takes the longer pasted text', async () => {
+    const fs = await import('node:fs');
+    const path = await import('node:path');
+    const sheet = fs.readFileSync(path.resolve(__dirname, '../../components/calendar/CalendarEditSheet.tsx'), 'utf8');
+    const field = sheet.slice(sheet.indexOf('value={hexInput}'), sheet.indexOf('/>', sheet.indexOf('value={hexInput}')));
+    expect(field).toMatch(/onBlur=\{\(\) => setHexInput\(\(v\) => hexFieldText\(v\)\)\}/);
+    expect(field).toMatch(/maxLength=\{HEX_FIELD_MAX_LENGTH\}/);
+  });
+});
diff --git a/src/lib/calendar-custom-color.ts b/src/lib/calendar-custom-color.ts
index 2217b414..7ede5bb5 100644
--- a/src/lib/calendar-custom-color.ts
+++ b/src/lib/calendar-custom-color.ts
@@ -10,6 +10,21 @@ export function normalizeHexColor(input: string): string | null {
   return `#${hex.toLowerCase()}`;
 }
 
+/**
+ * What the hex field shows once the user leaves it: a colour typed without
+ * its "#", in capitals or as three digits, spelled out as "#rrggbb"; anything
+ * else stays as typed, so the hint under the field still applies to it.
+ */
+export function hexFieldText(input: string): string {
+  return normalizeHexColor(input) ?? input;
+}
+
+/**
+ * Longest text the hex field takes: "#rrggbb" plus a space either side, as a
+ * pasted value can carry. Seven cut a pasted " #3b82f6" to an invalid colour.
+ */
+export const HEX_FIELD_MAX_LENGTH = 9;
+
 function hslToHex(h: number, s: number, l: number): string {
   const a = s * Math.min(l, 1 - l);
   const f = (n: number) => {