The about page explains why this site exists and how I work. This page is the rulebook behind it: the specific standards every calculator has to meet before it goes live, and the policies for sources, updates, and fixes.

The publishing checklist

A calculator doesn't go live until all of these are true:

  1. The formula is code I can test. Unit conversions happen inside the formula, not in the article. The code is the one place the math lives.
  2. The article matches the calculator. Every claim in the copy maps to something the code actually does.
  3. It passes a known-answer test. I run the tool with inputs where the right answer is already known, from a source example or a hand calculation, and the output has to match.
  4. It passes an input-response test. Changing an input has to move the result in the right direction and by the right amount.

Source standards

Primary sources come first. In rough order:

Source links sit at the bottom of each article.

Rounding and precision

Results are rounded to match how the number gets used. A topsoil estimate doesn't need four decimal places. Showing extra digits would suggest the tool is more exact than the inputs allow.

Updates and dates

When a formula, number, or article really changes, the page date is updated. Dates on this site mean meaningful updates, so "last updated" means what it says.

Calculators that use numbers that change over time, like tax figures, are labeled with the year of the data they use.

What happens to error reports

When someone reports a problem (calculateanything@outlook.com), I re-test the calculator against its sources. Confirmed errors get fixed, and real fixes update the page date. If the report changes a source or a formula, the article is updated to match.

For what this site is and isn't, including the limits of every estimate here, see the about page.