Free · offline · no sign-up
Online calculator
The quick calculator for the moments you just need an answer. Fully keyboard-driven, no ads in the way, and it keeps working when your connection does not.
Opens a fresh page with just this tool on it. Everything else is one click away.
How to use it
- 1 Type your sum with the keyboard or click the keypad.
- 2 Press Enter to evaluate; Escape clears.
- 3 For anything longer than one line, open the Workbook instead. It shows every step with a running total.
Frequently asked questions
Does this calculator work offline?
Yes. KontrolRoom is offline-first: once the page has loaded, the calculator runs locally in your browser with no network connection required.
Is it free?
Yes, and there is no account to create and no ads.
What if I need to do a whole series of calculations?
Use the Workbook. It is a calculating notepad where each line shows its own result, you can name a line and reuse it as a variable, and it handles unit and currency conversion in plain language.
It is not just this one tool
The online calculator is one block inside KontrolRoom, a modular workspace with notes, a calculating workbook, task boards and 20+ other utilities you can arrange on a single canvas. It all runs locally in your browser, works offline and costs nothing.
Explore the full workspace