About EurekaToolbox

EurekaToolbox is a growing set of free engineering calculators for civil, mechanical and electrical work. The idea is simple: a calculator should show its working, so you can check it rather than trust it.

What every calculator does

• Shows the formulas it uses, the assumptions behind them and the standards they relate to.
• Shows the working for your own inputs, so you can follow each step.
• Works in metric and imperial units, on phones as well as desktops.
• Runs entirely in your browser: no sign-up, nothing you enter is sent anywhere (see the privacy policy).

How the calculators are checked

Each calculator has a set of reference cases worked out by hand, which run automatically every time the code changes, so a mistake cannot slip in unnoticed. Engineering review notes and findings are recorded and fixed in the open, and each page includes a worked example you can reproduce.

We are also checking each calculator against published references. Once a calculator has been verified, its page will show the date of that review.

The results are preliminary estimates, not engineering advice; see the terms of use.

How guides are made

The guides explain how a calculation works, using a worked example taken from the calculator's own tested cases. They are drafted with an AI assistant, and every number in a guide is reproduced by the calculator's automated tests. Sources are linked at the end of a guide where there are any. They are not written or reviewed by a licensed engineer, so they explain the arithmetic and do not give design advice. If a qualified engineer ever reviews a guide, that guide will say so by name. Spotted a mistake? Please tell us.

Who is behind it

EurekaToolbox is built and maintained by Hii Tuong Sing. Corrections and ideas for new calculators are welcome: pleaseget in touch.