Calculator and unit converter for keypad phones, typed on the keypad
A calculator and unit converter for keypad phones like the Qin F21, Dumber Mini or Doov R77 Pro. There are no on-screen buttons: you type the calculation straight on the keypad and press OK for the result. Touch is switched off inside the app, so nothing gets pressed by accident in your pocket.
Keys
• 0–9 – type numbers
• * – add an operator, press it again for the next one (+ − × ÷)
• Hold * – a palette of symbols laid out like the keypad: ^, √, parentheses, %, ±
• # – decimal point
• OK or Call – show the result
• Back – delete the last character; hold it to clear everything
• ↑ / ↓ – go through the history
• ← / → – switch between Calculator, Unit converter and Settings
Features
• The usual order of operations and exact decimals (0.1 + 0.2 = 0.3)
• History like a paper tape, cleared when you close the app
• Unit converter for length, area, volume, mass, temperature, time, speed, pressure and energy, in both directions
• Copy the result, or take a converted value over to the calculator
• System, light, dark, dark red and custom themes, a keypad-friendly color picker, blue or any other icon color
• No ads, no tracking, no internet access
Based on Fossify Calculator (GPL-3.0), keypad input inspired by Calc-U-Later.
Screenshots
What’s new
First release: calculations typed straight on the keypad with the usual order of operations, a symbol palette on a held *, a history you can go through with up / down, and the unit converter and settings in tabs switched with left / right.
How to install
Download the APK from the button at the top of this page.
Allow “Install unknown apps” for your browser or file manager only, not for every app.
Open the downloaded file and confirm the installation.
If installation fails with “App not installed,” remove an earlier build of the same app first. A signature conflict is the usual cause.
Data safety
Every file is checked against its published SHA-256 before it is listed.
Files are scanned for malware on every update.
The permissions each app requests are listed on its own page.
Read the full safety policy for how we test, flag, and delist files.
Frequently asked questions
What is DumberKit: Calculator?
Calculator and unit converter for keypad phones, typed on the keypad
Who develops DumberKit: Calculator?
DumberKit: Calculator is developed by lbockaj.
Which Android version does DumberKit: Calculator require?
DumberKit: Calculator requires Android API 26 or later.
What is the current version of DumberKit: Calculator?
The synchronized F-Droid version is 1.0.0.
Which license does DumberKit: Calculator use?
The signed F-Droid metadata lists GPL-3.0-only.
Where is the source code for DumberKit: Calculator?
