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Schulrechner

The calculator you know from school
New in version 1.14.0
Feature: °′‴-button now switches to DMS format
Feature: Added option to toggle between Deg, Rad and Gra angle modes
Feature: Added Eng-button for engineering notation
Tweak: Updated dependencies
This is a very early version in development.
Unlabeled buttons will be implemented in the future, and bugs may be frequent. If you experience issues or have feature requests, please file an issue (link below).


Frustrated by the lack of free, open-source scientific calculators that feel like the ones I am used to, I decided to reverse-engineer my old calculator from school.

With features like:

- input of complex equations,

- output as fractions as well as decimals,

- result storage and reuse,

- selection and editing of equations from input history,

- and support for implicit multiplication (like 5π instead of 5*π),

this calculator produces math that looks like the math on your paper. That makes it much more suitable for higher-level math in school and university—especially if you've grown accustomed to this kind of interface from a young age and just forgot your calculator at home.

Some additional features include:

- A well-established open-source math.js library as the math engine—so you’re not relying on some sketchy, hand-rolled math logic (just my sketchy hand-rolled input method 😛)

- A familiar, intuitive design

- 100% offline usability and fully open source

- Written entirely in HTML, JS, and CSS, which means:

+ inherently cross-platform and also available as a website and Flatpak

+ easy for other web developers to contribute

+ admittedly a bit heavy for a calculator. If you're interested in helping make a lighter version (Flutter, Kotlin, etc.), you're very welcome!

Versions

Although APK downloads are available below to give you the choice, you should be aware that by installing that way you will not receive update notifications and it's a less secure way to download. We recommend that you install the F-Droid client and use that.

Download F-Droid
  • Version 1.14.0 (11400) suggested Added on Jan 26, 2026

    This version requires Android 7.0 or newer.

    It is built and signed by F-Droid, and guaranteed to correspond to this source tarball.

    Permissions
    • io.cardijey.schulrechner.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

    Download APK 3 MiB PGP Signature | Build Log

  • New in version 1.12.0
    Feature: Added config option to prefer decimal results
    Feature: Added mode menu
    Feature: Added CMPLX mode and i
    Feature: Added integration
    Feature: Added differentiation
    Feature: Added setup menu
    Feature: Added Norm and Fix rounding setup modes
    Feature: Added sexagesimal (hours, minutes, seconds) button
    Bugfix: Eliminated rounding errors in trigonometric functions
    Bugfix: Cube root of –1 now computes to –1
    Tweak: Updated dependencies
  • Version 1.12.0 (11200) - Added on Oct 10, 2025

    This version requires Android 7.0 or newer.

    It is built and signed by F-Droid, and guaranteed to correspond to this source tarball.

    Permissions
    • io.cardijey.schulrechner.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

    Download APK 3 MiB PGP Signature | Build Log

  • New in version 1.11.0
    Feature: Added (-) button
    Feature: Added keyboard support for desktop version
    Feature: Added hyperbolic functions
    Tweak: "Renovate" integrated to ensure up-to-date dependencies
    Tweak: Updated dependencies
  • Version 1.11.0 (11100) - Added on Aug 17, 2025

    This version requires Android 7.0 or newer.

    It is built and signed by F-Droid, and guaranteed to correspond to this source tarball.

    Permissions
    • io.cardijey.schulrechner.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION

    Download APK 3 MiB PGP Signature | Build Log