Contact
One address, for everything: [email protected]. There is no form to fill in and no account to make — email is simpler and it does not set a cookie.
What is worth an email
A result you think is wrong is the most useful thing you can send. Tell me the calculator, the numbers you put in, and what you got — the formula is on every page, so a disagreement is easy to run down. Corrections get priority over everything else, because being right is the only thing this site has.
Requests and everything else
If there is a bend you keep working out by hand that is not here yet, say so; the page inventory grows from real requests. Questions about how a calculator works are welcome too. Replies come when they come — this is a small, one-subject site, not a support desk.
A bend a month
One short email when a new calculator or reference goes up. No spam, no selling your address, unsubscribe in one click. That is the whole deal.