Contact
Email hello@machinecalcs.com. It is the one address for everything below.
Corrections
If a value, formula or table looks wrong, send the page address, the inputs you used and the reference you are comparing against. Accuracy is the point of the site, so these reports matter most.
Bugs and requests
For a calculator that misbehaves, tell us the page, your browser and the inputs that caused it. Suggestions for a missing calculation or a clearer explanation are welcome too.
Privacy
Questions about analytics, cookies or advertising go to the same address. The privacy policy explains what the site collects.
How the calculators are built and tested is described on the about & methodology page.