Terms of Use
Short version: the calculators are free, use them sensibly, and double-check anything that matters.
Using the site
You're welcome to use these calculators for any lawful personal or professional purpose, at no cost. Don't attempt to disrupt the site, misrepresent its results as something they're not, or pass off its content as your own.
Accuracy
The tools apply standard, well-known formulas, and the FAQ shows the math so you can verify any result yourself. Even so, everything is provided as-is, without warranties of any kind. Numbers you'll act on (a flooring order, a graded assignment) deserve a second check before you commit.
Your responsibility
Decisions you make based on results from this site are yours. To the fullest extent permitted by applicable law, the site and its operator accept no liability for losses arising from use of, or inability to use, these tools.
Changes
The tools and these terms may change from time to time without notice. Continuing to use the site after a change means you accept the updated terms.
Related pages
How your data is handled (spoiler: it stays on your device) is covered in the privacy policy.