The address for everything is statgarden.info@gmail.com.
What is most useful to send
A correction to a calculator
These are the most valuable messages to receive. If a result looks wrong, include the page it happened on, the figures you entered, the answer you got, and the answer you expected. A source for the correct method helps enormously, since the fix is usually to the formula rather than to the arithmetic.
A page that is broken
If something does not load, does not calculate, or displays oddly, it helps to know which page, which browser, and whether it happens on a phone or a computer.
A calculator that does not exist yet
Suggestions for new tools are welcome. The ones most likely to get built are those with a single, well-defined formula and a clear published source, since that is what can be shown honestly on the page.
Anything else
Questions about how a formula works, or about where a particular figure came from, are fine to send as well.
What is not worth sending
StatGarden does not accept guest posts, paid links, or sponsored content, and does not sell advertising placements within calculator pages. Messages of that kind will not get a reply.
Before you write
Every calculator page prints the formula it evaluates, explains each input, and works through examples. If a result seems surprising, that section is usually the fastest way to see why the number came out the way it did.