About

QuickReckon is a growing collection of free, single-purpose tools: countdowns, money and loan calculators, date math, unit converters and more. Each page explains the formula it uses and shows a worked example, so you can check the answer yourself.

A new tool is added most days. Before a tool is published, its calculator is tested automatically against a separate implementation of the same formula on a set of test cases, and the page is checked for accessibility basics, broken links and page weight. There are 5 tools today.

The tools run entirely in your browser. What you type is not sent to us or stored on a server.

Spotted a mistake or want a tool we do not have yet? Tell us.