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Converter of Units

Measurements, dates and tank

Close to 500 units in 38 measurements, currency included, together with date calculators, tank capacity and a mixture calculator, in one app for iPhone and iPad. From the makers of All in One Calculator.

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Converter of Units on iPhone, converting 2.5 hectares into ares, decares, square kilometers, square meters, square centimeters and square millimeters at once.

Every unit at once

Enter a value in any unit and every other unit in the measurement fills in. Area, length, mass, temperature, pressure, energy, data storage, fuel economy, electricity, magnetism, flow, shoe sizes and more: 38 measurements in all.

The Area measurement on iPad beside the sidebar's list of measurements: 7,275 ares shown at once as hectares, square meters, acres, square feet, marla and eight more units.
Enter one value and every unit fills in at once.

Find it fast

Search measurements by name or by the units they contain. A search for “inch” lists every measurement with an inch unit, and opening one shows just the matching units. Mark favorites to keep only the units you use in view.

Searching for inch on iPad: the sidebar lists Area, Density, Length and the other measurements with an inch unit, and Length opens showing only Feet Inch, Inch and Thou - Inch.
One search across measurements and units.

Currency, with flags

Exchange rates for the world’s currencies, each shown with its country’s flag, and a note of when the rates were last updated. Search the units on screen to narrow the list to the currencies you need.

Currencies on iPhone filtered by dollar: Australian, Bahamian, Barbadian, Belize, Bermudan, Brunei, Canadian and other dollars, each with its flag and a converted amount.
Every dollar side by side, with its flag.

Everything a result can do

Touch and hold a unit to copy its value, paste one in, hear it spoken, share it, or mark the unit as a favorite. Set the number of decimals with a slider, a menu, or by pinching the converter, and undo or redo any change.

The menu for the Decares unit on iPhone, offering Copy, Paste, Paste base, Speak, Share and Favorite.
Copy, paste, speak, share or favorite any unit.

Dates

Add or subtract years, months, weeks, days and hours from a date, or find the time between two dates, shown in every unit at once, with the option to count the end date.

Dates on iPad adding 1 year, 2 months, 3 weeks and 4 days to October 5, 2026, giving December 30, 2027.
Add to or subtract from any date.
The difference between two dates on iPhone: 2 months 1 week 2 days, which is 0.1918 years, 2.3 months, 10 weeks or 70 days.
The time between two dates, in every unit.

Tank capacity

The full and partly filled volume of horizontal and vertical cylinders, rectangular, oval and capsule tanks, and spheres, in gallons, cubic feet, liters and cubic meters. Each dimension can use a unit of its own.

Tank Capacity on iPad for a horizontal cylinder 6 meters long and 2 meters across, filled to 1 meter: 4,979.5 US gallons full and 2,489.8 at that depth, with cubic feet, UK gallons, liters and cubic meters.
The full volume, and the volume at any depth.

Mixture

The volume needed to make a mixture at a given ratio, from the amount of one component you already have, such as oil for two-stroke fuel. Send the result to the converter to see it in other units.

The Mixture calculator on iPhone: 4,000 of volume A at a 50:1 ratio needs 80 of volume B.
The volumes for any mixing ratio.

Your favorites, on every device

Favorite units and measurements sync through your own iCloud account, so they match on your iPhone and iPad, and in All in One Calculator too. Only the names of your favorites are synced, never your conversions, and you can turn syncing off in Settings.

Built for iPhone and iPad

Room to work

A sidebar on iPad and a tab bar on iPhone, several windows at once, windowed apps, Stage Manager and multitasking.

Fits your habits

Keyboard shortcuts, Quick Notes, drag and drop, Spotlight, Home Screen quick actions, and undo and redo throughout.

Accessible

VoiceOver and larger text, light and dark appearance, and detailed in-app help with its own table of contents and search.

Free, and without ads

The app is free and carries no advertising, and it asks you for nothing about yourself. Updates continue to add features.

View on the App Store