Contact
One person reads this inbox. Corrections to formulas and factual claims are handled first.
Use this address for corrections, requests and anything that is broken. Corrections to a formula or a factual claim are handled before new features.
What to include
- Wrong result: the page URL, the exact inputs you used, the result you got, and the result you expected.
- Wrong claim: the sentence, plus a link to a source. We change claims that can be sourced.
- Broken link: the page you were on and where the link pointed.
- New calculator idea: what you were trying to work out and the inputs you would want to enter.
Reporting a wrong result
A report that says "the calculation is broken" cannot be fixed. A report that says what you typed and what came back can be fixed the same day. Four things make a result reproducible:
- The page. Paste the address from the address bar, not the page title.
- Every input. All the numbers in the form, in order, including the currency you had selected.
- The result you got. The figure on the result card, and which of the metric tiles you are questioning.
- What you expected instead, and how you arrived at it. If you worked it out on paper, the working is more useful than the conclusion.
With those four, most reports turn out to be one of two things: a default that was not replaced before reading the result, or a genuine arithmetic error — and the second one gets fixed and the page gets a note.
Requesting a calculator
Requests are welcome and some of them get built. What makes a request actionable is the question behind it rather than the name of a tool: what are you trying to decide, what numbers do you have on hand, and what do you currently do instead — a spreadsheet, a guess, or a competitor's calculator you do not trust?
Two things that help the request get built: the inputs you would actually type in, and the single output you need. A calculator that answers one question well is more useful than one that answers five badly, which is why every tool on this site covers one question.
What we cannot help with
Two questions come up more than any others, so answering them here saves everyone a round trip. We cannot tell you what to charge. Pricing depends on your market, your competition, your time and your costs, and none of those are visible from here. The calculators will turn your numbers into a cost and a break-even price; the decision about the margin is yours.
We also cannot give supplier advice, diagnose a printer fault, or confirm whether a specific spool you are looking at is worth buying. A wrong guess from us is worse than no answer, and these are all things you can establish yourself faster than a reply would arrive.
- Quotes for printing work, or advice on pricing your specific business.
- Slicer, firmware or hardware support — the manufacturer or community forums are the right place.
- Requests to remove a calculator's assumptions. They are yours to change on the page.
Response time
Corrections are normally reviewed within a few days. Feature requests are collected and revisited in batches.