Offline currency converters for iPhone, compared

We make one of the apps on this list. It is not first, and we have tried to be straight about where the others win.

"Works offline" is claimed by nearly every converter on the App Store and means at least three different things in practice. This list is about which ones hold up when the signal actually goes.

1. The iPhone Calculator — free, and probably enough

Since iOS 18, Apple's Calculator converts around 105 currencies using cached rates, so it works with no connection. It costs nothing and is already installed. For occasional conversions it is the correct answer and no paid app improves on it meaningfully.

Best for: almost everybody. Weak at: one-handed use, automatic local-currency detection, and telling you whether a price is reasonable. Full comparison.

2. XE Currency — the data-heavy default

Excellent rate data, charts and history, plus money transfer. Free with advertising, with a paid tier to remove it. Recent reviews report intrusive ads and unreliable behaviour without a connection, which is worth knowing given the category.

Best for: charts, history, transfers, Android users. Weak at: being fast and quiet. Full comparison.

3. Currency Converter Plus — broad, subscription-funded

A large currency list plus crypto and commodities, charts, and an Android version. The full experience is a recurring fee, around $15 a year at the time of writing.

Best for: people who want crypto and commodities in the same app. Weak at: being a one-time purchase. Full comparison.

4. RoamRate — ours

Offline-first, no ads, no account, no analytics, and a keypad built to be used with one thumb. Adds a Local Price Index for judging whether a quoted price is reasonable, and a tipping calculator. Free for US dollars, euros, pounds, yen and Canadian dollars; $4.99 once for all 150+ currencies and everything else.

Best for: frequent travellers converting on their feet who object to subscriptions. Weak at: charts, history, crypto, money transfer, Android, iPad. We do none of those.

5. Your own head — free, and never runs out of battery

The most reliable offline converter is a memorised rule. For most currencies it is a single division that gets you within a few percent, which is all you need to decide whether a price is sane. We publish a cheat sheet per currency with the rule, its error band, and the point at which it stops being the right rule.

How to choose

Be honest about which traveller you are. Occasional converters should use the Calculator and spend the money on lunch. People who want financial data should use XE. People who convert constantly, one-handed, in places with no signal, and who resent renting a utility, are the narrow group we built for — and even they should learn the rule of thumb.