Apps in this category may contain mild or occasional cartoon, fantasy or real-life violence, as well as occasional or mild adult, sexually suggestive or horrifying content and may not be suitable for children under 9 years of age.

12+

Apps in this category may contain occasional mild indecent language, frequent or intense cartoon or real-life violence, minor or occasional adult or sexually suggestive material, and simulated gambling, and may be for children under 12 years of age.

17+

You must be at least 17 years old to access this App.

Apps in this category may contain frequent and intense offensive language; Frequent and intense cartoon, fantasy or realistic violence: frequent and intense adult, scary and sexually suggestive subjects: as well as sexual content, nudity, tobacco, alcohol and drugs, may not be suitable for children under 17 years of age.

Three (Rule of 3 Calculator) Screenshots

iPad

iPhone

About Three (Rule of 3 Calculator)

For example:
If my car consumes an average 8.8 litres of gas per 100 kilometers, a 350 kilometer trip will consume 30.8 litres (and therefore $61.6 if gas price is $2/litre)...

...or a fast currency converter: if 1 Euro is about 1.09 US dollars, 33.9 EUR is 36,92 USD.

Three can also be used for measurements, image sizes, grocery shopping and more.
As simple and trivial it is, the rule is used daily in practical arithmetics.

The application has a simple and modern interface to perform fast calculations and includes some basic options to facilitate the displaying results (thousands separator, decimal digits) including color customization in dark/light modes.

What's New in the Latest Version 3.2.0

Last updated on Sep 21, 2023

Old Versions

iOS 17 support plus some minor fixes and improvements.

Version History

3.2.0

Sep 21, 2023

iOS 17 support plus some minor fixes and improvements.

3.0.0

Jun 26, 2023

After a long hiatus, the app was written from scratch including full support for iOS 15 and 16.

2.1.1

Jan 15, 2018

- iOS 11 and iPhone X compatibility.
- New Dark Mode Interface.
- Customise the interface with the color you like.

2.1.0

Jan 2, 2018

- iOS 11 and iPhone X compatibility.
- New Dark Mode Interface.
- Customise the interface with the color you like.

2.0

Jan 8, 2017

Version 2.0 brings a complete interface redesign for all iOS devices, with live result preview as you type and removal of all advertisements.

1.1.1

Oct 5, 2014

The application is now compatible with for iOS 8.

1.1

Sep 8, 2014

The app:
- can now handle very large numbers,
- has a new iPhone/iPod UI layout,
- uses a decimal keyboard on iPhones and iPods,
- has an option to permanently remove advertisements with an in-app purchase.

1.0.3

Jun 3, 2014

Various fixes and improvements

1.0.2

Mar 20, 2014

Fixed minor bugs

1.0.1

Feb 17, 2014

Fixes a bug that prevented decimal values to be displayed.

1.0

Jan 3, 2014

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