Get in touch

There is no contact form here, and that is deliberate. A form on a site like this one has to pass your message through somebody else's service to reach us. Since the whole promise of this site is that what you type stays on your device, quietly making an exception for the page where you might write something personal seemed like the wrong thing to do. An email goes from you to us, and you can see exactly where it is going before you send it.

What is worth writing about

An answer that looks wrong

This is the most important kind of message we get, and it is never a bother. If you can, tell us which calculator it was, the numbers you put in, the answer it showed, and what you expected instead. That is usually enough for us to find the problem the same day.

A question or a label you could not understand

If you had to read something twice, that is our mistake and not yours — the entire point of this site is that it should not need reading twice. Tell us which words tripped you up. A good number of the labels on this site have been rewritten because a reader said exactly that.

A calculator you cannot find anywhere simple

If you searched for something and every result was a wall of jargon, tell us what you were trying to work out, in your own words. We will not always be able to build it, but several calculators here exist because somebody asked.

Something that does not work on your device

If a page looks broken, a button does nothing, or text is cut off, it helps to know your phone or computer, which browser you use, and roughly what the screen looked like. A screenshot is worth a great deal.

Anything about privacy

Questions about what is stored and what is not are always welcome, and we will answer them honestly. The privacy policy sets it out in full.

Other reasons to get in touch

• Teachers and schools — you are welcome to use these calculators in class or link to them in worksheets, and you do not need to ask. If a particular grading scale used at your institution is missing, tell us the rule and we will look at adding it.
• Translation — the site is built to hold more than one language, and a language is added only once it has a real translation rather than a machine-made one. If you would like to help translate it into yours, we would be glad to hear from you.
• Advertising and business enquiries — the same address reaches us.

What we cannot help with

We are not able to work out your homework, your tax, your loan or your official grade for you, and we cannot tell you what result your school will record — only your school can do that. What we can do is make sure the tool you used to check it is correct and understandable, so please do write if it was not.

Before you write

The common questions page answers most of what people ask, including what percent actually means, how to work out a tip or a sale price, and what happens to your numbers. If your question is already there you will have an answer immediately instead of waiting for a reply — and if the answer there is unclear, that is worth telling us about too.