Percentages, geometry, dates and unit conversions with the working shown.
Every tool below runs entirely in your browser. Nothing you type or upload is sent to a server, there is no account to create, and no page reloads.
All math & calculators tools
| Tool | What it does |
|---|---|
| Area & Perimeter Calculator | Calculate area, perimeter, diagonals and angles for rectangles, squares, circles and triangles. Shows the working. |
| Number to Words | Convert any number to words in English. Also shows ordinal form, currency and Roman numerals. Instant and completely offline. |
| Percentage Calculator | All common percentage calculations in one place: percent of a number, percentage change, ratio to percentage and increase/decrease. |
The tools in detail
Area & Perimeter Calculator
Calculate area, perimeter, diagonals and angles for rectangles, squares, circles and triangles. Shows the working.
Open Area & Perimeter Calculator →
Number to Words
Convert any number to words in English. Also shows ordinal form, currency and Roman numerals. Instant and completely offline.
Percentage Calculator
All common percentage calculations in one place: percent of a number, percentage change, ratio to percentage and increase/decrease.
Why these run in your browser
Every tool on this site is client-side. That is a deliberate choice, and it has three practical consequences.
Your data stays on your machine. There is no upload step, no server processing and nothing stored. You can confirm this yourself: open your browser's developer tools, switch to the Network tab and use any tool. Nothing is sent.
Results are instant. There is no round trip to wait for, so the output appears as fast as the browser can compute it.
It is free. There is no server cost per request to pass on, which is why there is no paywall and no usage cap.