Contact
One address, read by a person.
There is no contact form here on purpose. A form would mean collecting and storing what you write, and this site is built not to collect anything — so an email address it is.
Reporting a wrong result
This is the most useful kind of message to send. If a conversion factor, a calculator or a generated document looks wrong, include the page address and the values you put in, and it can be checked against the source directly. Conversion factors and tax rules do get corrected on the strength of these reports.
Requesting a tool
Requests are worth making. The most useful ones describe the job rather than the tool — what you were trying to get done, and what you ended up doing instead. That tends to produce a better tool than a feature name would.
Privacy, advertising and press
Questions about data and cookies are answered on the privacy policy page; anything it does not cover, send to the address above. Advertising and partnership enquiries go to the same place.