Contact Zhaku
The fastest route depends on what you need. Pick a subject below, or email us directly - every message is read by a person.
A calculator looks wrong
Please include the calculator name, the figures you entered and the result you expected. Do not include passwords, bank details, full addresses or anything else private. A screenshot with personal information removed can be useful.
The quickest way to report a suspected maths or wording issue is [email protected].
Questions about the calculations
Each calculator has an explanation, assumptions and frequently asked questions underneath it. If something is still unclear, tell us which page you were using and we will point you to the relevant formula or source.
Suggestions and feature requests
Have an idea for a calculator, a clearer label or a mobile improvement? We welcome practical suggestions. We cannot promise every request will be built, but useful ideas help us decide what to improve next.
Email [email protected] with the subject “Suggestion”.
Anything else
For general questions, site problems, corrections or a hello:
We are a small independent site, so replies can take a couple of working days. We do read every message.