diff --git a/client/src/components/Plugins/PluginFrame.tsx b/client/src/components/Plugins/PluginFrame.tsx
index d5e6889c8..21e1d11d6 100644
--- a/client/src/components/Plugins/PluginFrame.tsx
+++ b/client/src/components/Plugins/PluginFrame.tsx
@@ -3,6 +3,7 @@ import { useNavigate } from 'react-router-dom'
 import { useTranslation } from '../../i18n'
 import { useAuthStore } from '../../store/authStore'
 import { useSettingsStore } from '../../store/settingsStore'
+import { useTripStore } from '../../store/tripStore'
 import { useToast } from '../shared/Toast'
 import ConfirmDialog from '../shared/ConfirmDialog'
 import { pluginsApi } from '../../api/client'
@@ -141,6 +142,10 @@ export default function PluginFrame({ pluginId, tripId = null, placeId = null, d
   const userAvatar = useAuthStore((s) => s.user?.avatar_url ?? null)
   const isAdmin = useAuthStore((s) => s.user?.role === 'admin')
   const settings = useSettingsStore((s) => s.settings)
+  // Plugins format money against a concrete code, so resolve the same chain Costs
+  // uses: the user's display currency, else the trip's own.
+  const tripCurrency = useTripStore((s) => s.trip?.currency)
+  const displayCurrency = (settings.default_currency || tripCurrency || 'EUR').toUpperCase()
   const [height, setHeight] = useState<number | null>(null)
   // A host-rendered ConfirmDialog on the plugin's behalf: sandboxed frames have no
   // allow-modals and can't overlay the host, so destructive plugin actions get the
@@ -177,7 +182,7 @@ export default function PluginFrame({ pluginId, tripId = null, placeId = null, d
     appearance: readAppearance(),
     formats: {
       locale,
-      currency: settings.default_currency,
+      currency: displayCurrency,
       timeFormat: settings.time_format,
       distanceUnit: settings.distance_unit,
       temperatureUnit: settings.temperature_unit,
diff --git a/client/src/components/Settings/DisplaySettingsTab.tsx b/client/src/components/Settings/DisplaySettingsTab.tsx
index 3801830cb..09b9cf2ad 100644
--- a/client/src/components/Settings/DisplaySettingsTab.tsx
+++ b/client/src/components/Settings/DisplaySettingsTab.tsx
@@ -40,13 +40,18 @@ export default function DisplaySettingsTab(): React.ReactElement {
       {/* Display currency */}
       <div>
         <label className="block text-sm font-medium mb-2 text-content-secondary">{t('settings.currency')}</label>
+        {/* Unset ('') means "no personal preference": Costs then shows each trip in its
+            own currency, instead of forcing every trip through one display currency. */}
         <CustomSelect
-          value={settings.default_currency || 'EUR'}
+          value={settings.default_currency || ''}
           onChange={async v => {
             try { await updateSetting('default_currency', String(v)) }
             catch (e: unknown) { toast.error(e instanceof Error ? e.message : t('common.error')) }
           }}
-          options={currenciesWith(settings.default_currency).map(c => ({ value: c, label: `${c} — ${SYMBOLS[c] || c}` }))}
+          options={[
+            { value: '', label: t('settings.currencyTrip') },
+            ...currenciesWith(settings.default_currency || '').map(c => ({ value: c, label: `${c} — ${SYMBOLS[c] || c}` })),
+          ]}
           searchable
         />
         <p className="text-xs text-content-faint mt-2">{t('settings.currencyHint')}</p>
diff --git a/client/src/store/settingsStore.ts b/client/src/store/settingsStore.ts
index eba06eb77..113e8ba3b 100644
--- a/client/src/store/settingsStore.ts
+++ b/client/src/store/settingsStore.ts
@@ -28,7 +28,8 @@ export const useSettingsStore = create<SettingsState>((set, get) => ({
     default_lng: 2.3522,
     default_zoom: 10,
     dark_mode: false,
-    default_currency: 'USD',
+    // Empty = no personal display currency, so Costs falls back to the trip's own.
+    default_currency: '',
     language: localStorage.getItem('app_language') || 'en',
     temperature_unit: 'fahrenheit',
     distance_unit: 'metric',
diff --git a/client/src/types.ts b/client/src/types.ts
index 56c4b3c16..e6a982ae1 100644
--- a/client/src/types.ts
+++ b/client/src/types.ts
@@ -110,7 +110,8 @@ export interface Settings {
   default_lng: number
   default_zoom: number
   dark_mode: boolean | string
-  default_currency: string
+  /** Display currency for Costs. Empty/null = follow each trip's own currency. */
+  default_currency: string | null
   language: string
   temperature_unit: string
   distance_unit?: DistanceUnit
diff --git a/client/tests/unit/stores/settingsStore.test.ts b/client/tests/unit/stores/settingsStore.test.ts
index cc020f5ff..d4cfa898f 100644
--- a/client/tests/unit/stores/settingsStore.test.ts
+++ b/client/tests/unit/stores/settingsStore.test.ts
@@ -158,7 +158,10 @@ describe('settingsStore', () => {
 
       const state = useSettingsStore.getState();
       expect(state.settings.dark_mode).toBe(true);
-      expect(state.settings.default_currency).toBe('USD');
+      expect(state.settings.language).toBe('en');
+      // No display currency of their own: Costs then follows each trip's own currency
+      // rather than forcing every trip through one code.
+      expect(state.settings.default_currency).toBe('');
     });
   });
 
diff --git a/shared/src/i18n/ar/settings.ts b/shared/src/i18n/ar/settings.ts
index c240e9112..2d4b46d83 100644
--- a/shared/src/i18n/ar/settings.ts
+++ b/shared/src/i18n/ar/settings.ts
@@ -290,6 +290,7 @@ const settings: TranslationStrings = {
   'settings.about.supporter.tier.hostelBunkmate': 'Hostel Bunkmate', // en-fallback
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'عملة الرحلة',
   'settings.passkey.title': 'مفاتيح المرور',
   'settings.passkey.description':
     'سجّل الدخول بشكل أسرع وأكثر مقاومة للتصيّد باستخدام مفتاح مرور — ببصمة إصبعك أو وجهك أو رمز PIN أو مفتاح أمان مادي. تبقى كلمة المرور كنسخة احتياطية.',
diff --git a/shared/src/i18n/br/settings.ts b/shared/src/i18n/br/settings.ts
index 8c0e76ef4..d70bba98a 100644
--- a/shared/src/i18n/br/settings.ts
+++ b/shared/src/i18n/br/settings.ts
@@ -303,6 +303,7 @@ const settings: TranslationStrings = {
   'settings.notificationPreferences.ntfy': 'Ntfy',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Moeda da viagem',
   'settings.passkey.title': 'Passkeys',
   'settings.passkey.description':
     'Entre mais rápido e com proteção contra phishing usando uma passkey — sua impressão digital, rosto, PIN ou uma chave de segurança física. Sua senha continua disponível como reserva.',
diff --git a/shared/src/i18n/cs/settings.ts b/shared/src/i18n/cs/settings.ts
index 623f704c3..dd30317fb 100644
--- a/shared/src/i18n/cs/settings.ts
+++ b/shared/src/i18n/cs/settings.ts
@@ -297,6 +297,7 @@ const settings: TranslationStrings = {
   'settings.notificationPreferences.ntfy': 'Ntfy',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Měna cesty',
   'settings.passkey.title': 'Přístupové klíče',
   'settings.passkey.description':
     'Přihlašujte se rychleji a s ochranou proti phishingu pomocí přístupového klíče — otiskem prstu, obličejem, PINem nebo hardwarovým klíčem. Vaše heslo zůstává jako záloha.',
diff --git a/shared/src/i18n/de/settings.ts b/shared/src/i18n/de/settings.ts
index d360d9730..6e8a2c110 100644
--- a/shared/src/i18n/de/settings.ts
+++ b/shared/src/i18n/de/settings.ts
@@ -305,6 +305,7 @@ const settings: TranslationStrings = {
   'settings.notificationPreferences.ntfy': 'Ntfy',
   'settings.currency': 'Währung',
   'settings.currencyHint': 'Alle Beträge in Costs werden in diese Währung umgerechnet und angezeigt.',
+  'settings.currencyTrip': 'Reisewährung',
   'settings.passkey.title': 'Passkeys',
   'settings.passkey.description':
     'Melde dich schneller und phishing-resistent mit einem Passkey an — per Fingerabdruck, Gesicht, PIN oder Hardware-Schlüssel. Dein Passwort bleibt als Backup erhalten.',
diff --git a/shared/src/i18n/en/settings.ts b/shared/src/i18n/en/settings.ts
index d551b4731..1c9f168a4 100644
--- a/shared/src/i18n/en/settings.ts
+++ b/shared/src/i18n/en/settings.ts
@@ -309,6 +309,7 @@ const settings: TranslationStrings = {
   'settings.mfa.demoBlocked': 'Not available in demo mode',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Trip currency',
   'settings.passkey.title': 'Passkeys',
   'settings.passkey.description':
     'Sign in faster and phishing-resistant with a passkey — your fingerprint, face, PIN, or a hardware key. Your password stays as a backup.',
diff --git a/shared/src/i18n/es/settings.ts b/shared/src/i18n/es/settings.ts
index b00b49d3f..8bf3b8cc6 100644
--- a/shared/src/i18n/es/settings.ts
+++ b/shared/src/i18n/es/settings.ts
@@ -305,6 +305,7 @@ const settings: TranslationStrings = {
   'settings.notificationPreferences.ntfy': 'Ntfy',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Moneda del viaje',
   'settings.passkey.title': 'Passkeys',
   'settings.passkey.description':
     'Inicia sesión más rápido y con protección frente al phishing usando una passkey: tu huella, tu cara, tu PIN o una llave de seguridad física. Tu contraseña sigue disponible como respaldo.',
diff --git a/shared/src/i18n/fr/settings.ts b/shared/src/i18n/fr/settings.ts
index 6611a982c..15b46064c 100644
--- a/shared/src/i18n/fr/settings.ts
+++ b/shared/src/i18n/fr/settings.ts
@@ -308,6 +308,7 @@ const settings: TranslationStrings = {
   'settings.notificationPreferences.ntfy': 'Ntfy',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Devise du voyage',
   'settings.passkey.title': 'Passkeys',
   'settings.passkey.description':
     'Connectez-vous plus rapidement et de façon résistante au phishing avec une passkey — votre empreinte digitale, votre visage, votre code PIN ou une clé matérielle. Votre mot de passe reste disponible en secours.',
diff --git a/shared/src/i18n/gr/settings.ts b/shared/src/i18n/gr/settings.ts
index 6f3910e35..1f75e8dd4 100644
--- a/shared/src/i18n/gr/settings.ts
+++ b/shared/src/i18n/gr/settings.ts
@@ -312,6 +312,7 @@ const settings: TranslationStrings = {
   'settings.mfa.demoBlocked': 'Δεν είναι διαθέσιμο σε λειτουργία demo',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Νόμισμα ταξιδιού',
   'settings.passkey.title': 'Passkeys',
   'settings.passkey.description':
     'Συνδεθείτε πιο γρήγορα και με προστασία από phishing χρησιμοποιώντας ένα passkey — το δαχτυλικό σας αποτύπωμα, το πρόσωπό σας, ένα PIN ή ένα κλειδί υλικού. Ο κωδικός σας παραμένει ως εφεδρεία.',
diff --git a/shared/src/i18n/hu/settings.ts b/shared/src/i18n/hu/settings.ts
index c098f6e4c..a33d1d36c 100644
--- a/shared/src/i18n/hu/settings.ts
+++ b/shared/src/i18n/hu/settings.ts
@@ -304,6 +304,7 @@ const settings: TranslationStrings = {
   'settings.notificationPreferences.ntfy': 'Ntfy',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Az utazás pénzneme',
   'settings.passkey.title': 'Passkey-k',
   'settings.passkey.description':
     'Jelentkezz be gyorsabban és adathalászat-állóan egy passkey-jel — ujjlenyomattal, arccal, PIN-kóddal vagy hardveres kulccsal. A jelszavad tartalékként megmarad.',
diff --git a/shared/src/i18n/id/settings.ts b/shared/src/i18n/id/settings.ts
index afed07c63..59747ae5b 100644
--- a/shared/src/i18n/id/settings.ts
+++ b/shared/src/i18n/id/settings.ts
@@ -301,6 +301,7 @@ const settings: TranslationStrings = {
   'settings.bookingLabelsHint': 'Menampilkan nama stasiun / bandara di peta. Jika mati, hanya ikon ditampilkan.',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Mata uang perjalanan',
   'settings.passkey.title': 'Passkey',
   'settings.passkey.description':
     'Masuk lebih cepat dan tahan terhadap phishing dengan passkey — sidik jari, wajah, PIN, atau kunci keamanan fisik kamu. Kata sandimu tetap tersedia sebagai cadangan.',
diff --git a/shared/src/i18n/it/settings.ts b/shared/src/i18n/it/settings.ts
index 02040e3eb..a65c1ffea 100644
--- a/shared/src/i18n/it/settings.ts
+++ b/shared/src/i18n/it/settings.ts
@@ -303,6 +303,7 @@ const settings: TranslationStrings = {
   'settings.notificationPreferences.ntfy': 'Ntfy',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Valuta del viaggio',
   'settings.passkey.title': 'Passkey',
   'settings.passkey.description':
     'Accedi più velocemente e in modo resistente al phishing con una passkey — la tua impronta digitale, il volto, il PIN o una chiave hardware. La tua password resta come riserva.',
diff --git a/shared/src/i18n/ja/settings.ts b/shared/src/i18n/ja/settings.ts
index ddf4f7a86..39e7c05eb 100644
--- a/shared/src/i18n/ja/settings.ts
+++ b/shared/src/i18n/ja/settings.ts
@@ -278,6 +278,7 @@ const settings: TranslationStrings = {
   'settings.oauth.badge.machine': 'マシン',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': '旅行の通貨',
   'settings.passkey.title': 'パスキー',
   'settings.passkey.description':
     '指紋、顔認証、PIN、またはハードウェアキーを使うパスキーで、より速く、フィッシングに強いサインインができます。パスワードはバックアップとして残ります。',
diff --git a/shared/src/i18n/ko/settings.ts b/shared/src/i18n/ko/settings.ts
index 23444cd21..a3250db5f 100644
--- a/shared/src/i18n/ko/settings.ts
+++ b/shared/src/i18n/ko/settings.ts
@@ -294,6 +294,7 @@ const settings: TranslationStrings = {
   'settings.oauth.badge.machine': '머신',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': '여행 통화',
   'settings.passkey.title': '패스키',
   'settings.passkey.description':
     '지문, 얼굴, PIN 또는 하드웨어 키 같은 패스키로 더 빠르고 피싱에 강하게 로그인하세요. 비밀번호는 백업으로 그대로 유지됩니다.',
diff --git a/shared/src/i18n/nl/settings.ts b/shared/src/i18n/nl/settings.ts
index b41c8e220..5d92e283e 100644
--- a/shared/src/i18n/nl/settings.ts
+++ b/shared/src/i18n/nl/settings.ts
@@ -304,6 +304,7 @@ const settings: TranslationStrings = {
   'settings.notificationPreferences.ntfy': 'Ntfy',
   'settings.currency': 'Valuta',
   'settings.currencyHint': 'Alle bedragen onder Onkosten worden omgerekend naar en weergegeven in deze valuta.',
+  'settings.currencyTrip': 'Valuta van de reis',
   'settings.passkey.title': 'Passkeys',
   'settings.passkey.description':
     'Log sneller en phishingbestendig in met een passkey — je vingerafdruk, gezicht, pincode of een hardwaresleutel. Je wachtwoord blijft als back-up bestaan.',
diff --git a/shared/src/i18n/pl/settings.ts b/shared/src/i18n/pl/settings.ts
index 3663ade51..232d9369b 100644
--- a/shared/src/i18n/pl/settings.ts
+++ b/shared/src/i18n/pl/settings.ts
@@ -301,6 +301,7 @@ const settings: TranslationStrings = {
   'settings.mustChangePassword': 'Musisz zmienić hasło przed kontynuowaniem.',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Waluta wyjazdu',
   'settings.passkey.title': 'Klucze dostępu',
   'settings.passkey.description':
     'Loguj się szybciej i z odpornością na phishing za pomocą klucza dostępu — odcisku palca, twarzy, kodu PIN lub klucza sprzętowego. Twoje hasło pozostaje jako zapasowa opcja.',
diff --git a/shared/src/i18n/ru/settings.ts b/shared/src/i18n/ru/settings.ts
index 6d0fce764..821696610 100644
--- a/shared/src/i18n/ru/settings.ts
+++ b/shared/src/i18n/ru/settings.ts
@@ -302,6 +302,7 @@ const settings: TranslationStrings = {
   'settings.notificationPreferences.ntfy': 'Ntfy',
   'settings.currency': 'Валюта',
   'settings.currencyHint': 'Все расходы будут конвертированы и показаны в этой валюте.',
+  'settings.currencyTrip': 'Валюта поездки',
   'settings.passkey.title': 'Passkeys',
   'settings.passkey.description':
     'Входите быстрее и с защитой от фишинга с помощью passkey — отпечатка пальца, лица, PIN-кода или аппаратного ключа. Ваш пароль остаётся как резервный способ.',
diff --git a/shared/src/i18n/sv/settings.ts b/shared/src/i18n/sv/settings.ts
index 3995cc6a9..1ce6726a6 100644
--- a/shared/src/i18n/sv/settings.ts
+++ b/shared/src/i18n/sv/settings.ts
@@ -306,6 +306,7 @@ const settings: TranslationStrings = {
   'settings.mfa.demoBlocked': 'Finns inte i demoläge',
   'settings.currency': 'Valuta',
   'settings.currencyHint': 'Alla belopp under kostnader omräknas till och redovisas i denna valuta.',
+  'settings.currencyTrip': 'Resans valuta',
   'settings.passkey.title': 'Inloggningsnycklar',
   'settings.passkey.description':
     'Logga in snabbare och med bättre skydd mot nätfiske med en inloggningsnyckel – ditt fingeravtryck, ditt ansikte, din PIN-kod eller en hårdvarunyckel. Ditt lösenord finns kvar som reserv.',
diff --git a/shared/src/i18n/tr/settings.ts b/shared/src/i18n/tr/settings.ts
index ffa4d26ff..e2f9009eb 100644
--- a/shared/src/i18n/tr/settings.ts
+++ b/shared/src/i18n/tr/settings.ts
@@ -300,6 +300,7 @@ const settings: TranslationStrings = {
   'settings.oauth.badge.machine': 'makine',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Gezi para birimi',
   'settings.passkey.title': 'Passkey’ler',
   'settings.passkey.description':
     'Passkey ile daha hızlı ve kimlik avına dayanıklı şekilde oturum açın — parmak iziniz, yüzünüz, PIN’iniz veya bir donanım anahtarı. Şifreniz yedek olarak kalır.',
diff --git a/shared/src/i18n/uk/settings.ts b/shared/src/i18n/uk/settings.ts
index 8c583e8c7..5c4149492 100644
--- a/shared/src/i18n/uk/settings.ts
+++ b/shared/src/i18n/uk/settings.ts
@@ -302,6 +302,7 @@ const settings: TranslationStrings = {
   'settings.oauth.badge.machine': 'машина',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': 'Валюта подорожі',
   'settings.passkey.title': 'Passkeys',
   'settings.passkey.description':
     'Входьте швидше та з захистом від фішингу за допомогою passkey — відбитка пальця, обличчя, PIN-коду або апаратного ключа. Ваш пароль залишається як резервний варіант.',
diff --git a/shared/src/i18n/vi/settings.ts b/shared/src/i18n/vi/settings.ts
index 16c1b7978..2cd451176 100644
--- a/shared/src/i18n/vi/settings.ts
+++ b/shared/src/i18n/vi/settings.ts
@@ -308,6 +308,7 @@ const settings: TranslationStrings = {
   'settings.mfa.demoBlocked': 'Không có sẵn ở chế độ demo',
   'settings.currency': 'Tiền tệ',
   'settings.currencyHint': 'Tất cả số tiền trong Chi phí được chuyển đổi sang và hiển thị bằng loại tiền tệ này.',
+  'settings.currencyTrip': 'Tiền tệ của chuyến đi',
   'settings.passkey.title': 'Mật mã',
   'settings.passkey.description':
     'Đăng nhập nhanh hơn và chống lừa đảo bằng mật mã — vân tay, khuôn mặt, PIN hoặc khóa phần cứng của bạn. Mật khẩu của bạn vẫn là bản sao lưu.',
diff --git a/shared/src/i18n/zh-TW/settings.ts b/shared/src/i18n/zh-TW/settings.ts
index 02cc9f4de..e19d755cc 100644
--- a/shared/src/i18n/zh-TW/settings.ts
+++ b/shared/src/i18n/zh-TW/settings.ts
@@ -285,6 +285,7 @@ const settings: TranslationStrings = {
   'settings.bookingLabelsHint': '在地圖上顯示車站 / 機場名稱。關閉時僅顯示圖示。',
   'settings.currency': 'Currency',
   'settings.currencyHint': 'All amounts in Costs are converted to and shown in this currency.',
+  'settings.currencyTrip': '行程貨幣',
   'settings.passkey.title': 'Passkey',
   'settings.passkey.description':
     '使用 Passkey 更快登入，並可抵禦網路釣魚——透過你的指紋、臉部、PIN 碼或硬體金鑰。你的密碼仍會保留作為備援。',
diff --git a/shared/src/i18n/zh/settings.ts b/shared/src/i18n/zh/settings.ts
index 1eb77615e..64838ab32 100644
--- a/shared/src/i18n/zh/settings.ts
+++ b/shared/src/i18n/zh/settings.ts
@@ -283,6 +283,7 @@ const settings: TranslationStrings = {
   'settings.notificationPreferences.ntfy': 'Ntfy',
   'settings.currency': '货币',
   'settings.currencyHint': '费用中的所有金额都会换算并以此货币显示。',
+  'settings.currencyTrip': '行程货币',
   'settings.passkey.title': '通行密钥',
   'settings.passkey.description':
     '使用通行密钥更快登录，并能抵御钓鱼攻击——通过指纹、面容、PIN 或硬件密钥验证。你的密码仍可作为备用方式。',