Contact Us
Spotted an error, have a request, or want to suggest a calculator? Send a message and we'll read it. This form works without a backend: it opens your email client with the message already filled in, addressed to the site's inbox, so nothing you type is stored on a server.
Most messages fall into one of three categories: a correction (a formula, an example, or a translated string that reads wrong), a feature request (a new fixed-rate page, a new comparison page, a new language), or general feedback about how the calculators could work better. All three are welcome, and it helps to mention which page you were on and what number you were trying to calculate when something didn't look right.
Other Ways to Find an Answer
Looking for something specific? The formula page covers the math in full, the examples page has 20 worked problems, and the calculator handles most day-to-day questions directly. Most fixed-percentage questions (10% off, 20% off, and so on) are already covered on their own dedicated pages, linked from the homepage and the reference chart.
Response Time
This site is maintained by a small team, so replies are not instant, but every message is read. Corrections to a formula or a worked example are usually the fastest to act on, since they only require checking the arithmetic and updating one page.
Before You Write
A few quick checks save a round trip. If a calculator shows an unexpected result, try the same numbers on the formula page to confirm which value should go in the original slot and which in the new slot; the most common source of a "wrong" answer is swapping the two. If a translated page reads awkwardly, note the exact page and language so the string can be traced back to its source file. If you want a new calculator added, a short description of the formula and one worked example is enough to get started.