Best currency calculator app: offline rates and real fees (2026)

A currency calculator app has one job at the till: tell you what a price costs in your own money, right now, even when the shop's Wi-Fi is down and your roaming is off. Most apps can do that on a good connection. The ones worth keeping on your phone also show where the rate came from, keep working offline, and help with the part that actually costs you money abroad: card fees, ATM fees and the "pay in dollars?" question at the terminal.

This guide covers what to look for, how the reference rates behind these apps work, and what our free app, Currency & Money Converter (listed on our site as Currency Converter Worldwide), does on Android and iPhone.

What to look for in a currency calculator app

• It works offline. Saved rates should keep converting with no signal, and the app should show when they were last updated so you know how fresh they are.
• It shows a timestamp and a source. A number with no date can't be trusted for an invoice or a refund.
• It handles several currencies at once. On a multi-country trip you want one amount shown in every currency you're dealing with.
• It covers fees, not just rates. The rate on the screen is a mid-market reference. Your bank or card adds its own margin, and a good app helps you see that cost.
• It doesn't ask for an account. Converting a price shouldn't need an email address.

Where the rates come from (checked October 2, 2026)

Many apps and websites lean on central-bank reference rates for history and charts. The European Central Bank's euro foreign exchange reference rates are a common one. On the ECB's page today:

• It publishes reference rates for 32 currencies against the euro.
• The rates are usually updated at around 16:00 CET every working day, except on TARGET closing days.
• The latest rate shown is for October 1, 2026: 1 euro = 1.1298 US dollars.
• The ECB says the rates are "published for information purposes only" and that using them for transactions is "strongly discouraged".

That last point matters. A reference rate tells you roughly what something costs. It is not the rate your card will charge, which is why the fee tools below exist.

Currency & Money Converter: what it does

Our app is free on Google Play and the App Store. Here is what its Google Play listing says it includes, as of today:

• Converter: live exchange rates for 160+ currencies, refreshed hourly, with the time of the last update. It works offline on the last saved rates. A multi-currency view shows one amount in 11 currencies at once, and a camera scan reads the amount from a price tag or receipt.
• History: 7-day to 5-year charts for any pair from ECB reference rates, a rate-on-a-date converter for invoices, tax and refunds, and rate alerts when a pair hits your target.
• Travel money tools: a card and ATM fee calculator, a "pay in local or home currency?" check against dynamic currency conversion, a tip calculator with the local custom for 50+ countries, a tax-free shopping refund calculator with VAT rates for 45 countries, a trip budget per day and a bill splitter.
• Sending money: what the recipient actually gets after fees and margin, and an exchange-rate margin checker.
• Extras: gold and silver price calculators, a US dollar inflation calculator using BLS CPI data, a salary converter and a currency symbols and ISO code reference. 45 calculators in all.
• Privacy: no account or sign-in. Favourites and history stay on your device, with backup and restore to a file.

A worked example: what does that dinner really cost?

Say the bill in Lisbon is €80 and you pay with a US card. At the ECB reference rate for October 1, 2026 (1 EUR = 1.1298 USD), that's 80 × 1.1298 = $90.38 before any fees.

Now suppose your card charges a 3% foreign transaction fee (an example; check your own card's terms). That adds $90.38 × 0.03 = $2.71, for $93.09. If the terminal offers to charge you in dollars instead, its own rate may be worse again. The app's card fee and "pay in local or home currency?" calculators do this sum for you, with your card's real fee typed in.

How it compares with a reference-rate website

ECB figures are from the ECB's page as fetched on October 2, 2026; app figures are from the app's Google Play listing on the same day.

Prefer the browser?

The same tools run on the web at currencyconvertworldwide.com, including the exchange rate markup calculator and the dynamic currency conversion calculator. For trip planning, read our currency conversion guide for travelers. If you also convert units, recipes or sizes, see the best free unit converter apps for Android.

Price

Free to download and use, with ads. A one-time Pro purchase removes all ads and unlocks 6-decimal precision, custom themes and unlimited favourites. There is no subscription.