Report an error

A wrong number is the worst thing this site can have. Reports get fixed first.

Write to [email protected]. There is no form, so nothing you send passes through a third party.

What helps us fix it fast

• The address of the calculator page, or the "Copy link" link from the result panel, which includes the values you entered.
• The result you got and the result you expected, with the source you compared against if you have one.
• For layout problems, the device and browser you used.

What we do with a report

We check the formula against its source, correct the page, re-run the tests, and update the verification date at the bottom of the page. If the report changes a result, we reply to say so.

Other messages

Suggestions for new calculators, questions about how we calculate, and anything else are welcome at the same address. We do not answer requests for personal medical, legal or financial advice; a calculator is not a consultation.

Other contacts

• Advertising and partnership proposals: [email protected].
• Everything else: [email protected].