Unit Converter

Convert anything, instantly

A fast, beautiful unit and currency converter for iPhone, that works offline. 1,600+ units in 77 converters.

Download on the App StoreNo account · No ads · No tracking

Length is free. Unit Converter Pro unlocks the other converters, currency and the widget.

Unit Converter home screen with search and a quick inch to centimeter conversion

Smart search

Just type it

Search understands what you mean, and the answer appears as you type, with the formula one tap away.

How it works

Three steps, or fewer

  1. Type a conversion

    Use search, or open a converter and use the keypad.

  2. Read the answer

    It updates as you type. Copy it formatted, with its unit or at full precision.

  3. Keep it close

    Save it as a favorite, or open the pair page to see the formula.

Features

Every unit you need

1,600+ units in 77 converters

Length, weight, temperature and data, through to pressure, energy, light and radiation. Length is free; the others need Pro.

A keypad built for numbers

Type fractions, do arithmetic and enter feet-and-inches. Edit either side and swap units in one tap.

Currency, even offlinePRO

European Central Bank reference rates plus 150+ more, saved on your iPhone. Every rate shows its source and age.

See the formula

Pair pages show the formula, a worked example and a conversion table.

Quick Pair widgetPRO

Keep a conversion on your Home Screen, and flip it with the swap button.

Favorites and history

Save what you use most. History stays on your device, and you can turn it off or clear it.

Light and dark

Both themes, with a colour for every category and a live “aura”.

Exact results

Authoritative factors from NIST, BIPM and CLDR, computed exactly rather than with floating-point shortcuts.

Tour

See it in action

Home screen: Your conversions, one screen away
HomeConvert anything, instantlyYour conversions, one screen away
Smart search screen: “5 kg to lb”, answered as you type
Smart searchJust type it“5 kg to lb”, answered as you type
Keypad screen: Fractions, arithmetic and feet-and-inches
KeypadBuilt for numbersFractions, arithmetic and feet-and-inches
Currency · Pro screen: ECB reference rates plus 150+ currencies
Currency · ProLive rates, even offlineECB reference rates plus 150+ currencies
Pair pages screen: A worked example and a conversion table
Pair pagesSee the formulaA worked example and a conversion table
Catalog screen: Everyday, engineering and science units
CatalogEvery unit you needEveryday, engineering and science units
Widget · Pro screen: Quick Pair, with a one-tap swap
Widget · ProOn your Home ScreenQuick Pair, with a one-tap swap

Privacy

Yours, and private

Favorites, history, settings and saved rates stay on your iPhone. The app’s own network requests only download exchange rates, and they carry no personal information. Apple handles purchases.

No accountNo adsNo tracking

Read the privacy policy

Pricing

Start free. Unlock the rest.

Free

$0

  • The full Length converter
  • Search answers
  • History
  • Browse the catalog
  • Length favorites

Unit Converter Pro

Yearly$9.99/year7 days free for new subscribers
Monthly$1.99/month
Lifetime$24.99 once
  • All 77 converters, including Currency
  • Favorites in every converter
  • The Quick Pair widget

Prices in USD; the App Store shows your local price. Subscriptions renew automatically until cancelled in iOS Settings. Terms of Service

FAQ and support

Good questions

Does it work offline?

Yes. Converters and search need no connection. Currency uses the last rates saved on your iPhone, and shows how old they are.

What is free, and what needs Pro?

Length, search answers, history, browsing the catalog and Length favorites are free. Pro adds every other converter including Currency, favorites outside Length, and the Quick Pair widget.

Can I use the currency rates for transactions?

No. They are reference rates for information only, so your bank or card may charge a different rate.

How does the free trial work?

Pro Yearly includes 7 days free for new subscribers, then $9.99 a year. Cancel before the trial ends and you pay nothing.

How do I cancel a subscription?

In iOS Settings: tap your name, then Subscriptions. Apple handles billing, and the subscription stays active until the end of the period you paid for.

I got a new iPhone. How do I get Pro back?

Sign in with the same Apple Account, then tap Restore purchases in the app’s Settings.

Do you collect my data?

No. There is no account, analytics, ads or tracking. The app’s own network requests only download exchange rates, and they carry no personal information.

Which devices does it run on?

iPhone, on iOS 26 or later.

Still stuck? Email .

Download on the App Store