Enough for the first day — a taxi, a meal, a tip — roughly $50–100 equivalent, then withdraw locally from a bank ATM with a low-fee card. Cards work almost everywhere in Europe, East Asia and the Gulf; carry more cash in Japan's small towns, rural Southeast Asia and parts of Latin America.
Don’t exchange at the airport — rates are poor. Use a bank ATM after arrival, and always choose to be charged in the local currency (decline ‘dynamic currency conversion’).
Cards: a no-foreign-transaction-fee credit card for spending plus a debit or multi-currency card (Wise, Revolut) for ATM withdrawals. Tell your bank you’re traveling if it still requires it.
Cash-heavy places: Japan outside big cities, Germany’s smaller restaurants, markets everywhere, taxis in some countries, tips.
Card-first places: Nordic countries, UK, Netherlands, Singapore, Australia, Hong Kong (Octopus card), Dubai.
Carry cash in two places; keep a photo of your cards’ emergency numbers.
Related questions
Is travel insurance worth it?
For international trips, medical cover alone justifies it — a hospital stay abroad can cost tens of thousands. Trip-cancellation cover is worth it for expensive, non-refundable trips. Check what your credit card already includes before buying. Full answer →
Airline, airport and government rules change without notice. Treat this as a starting point and confirm with the airline or authority for your specific trip. Request a correction if something is out of date.