Contact us

The fastest way to reach us is email. We read every message about wrong results, broken pages and ideas for new tools.

Reporting a wrong result

A result we can reproduce is a result we can fix. Please include:

• The tool's name or page address
• The values you entered, including units
• The answer you got and the answer you expected, with its source if you have one
• Your browser and device

Each tool shows the formula it uses, and the methodology page lists the standards behind them, which can help pin down where a difference comes from.

Suggesting a tool

Tell us what you were trying to work out and which tool you used instead. New tools join the map on the line that fits them best.

Teachers and organisations

You are welcome to link to any tool or guide from lesson plans, coursework and websites. For anything else, email us first.