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Corrections policy

A calculator site loses credibility the moment it is wrong, and it does not regain it on the timescale it was lost. So corrections are treated as an operational metric, not as an inbox.

Reporting one

Email [email protected] with the page URL and the inputs you used. The URL carries the calculator state in its query string, so copying the address bar is usually enough to reproduce exactly what you saw.

What happens next

  1. The reported inputs become a failing test case before anything is changed. A bug that is fixed without a test that would have caught it is a bug that comes back.
  2. If the engine is wrong, the fix reaches every calculator on that engine at once. That is the point of sharing engines, and the test suite re-runs across all of them.
  3. If a statutory constant is wrong, the ruleset is corrected, dated and re-sourced, and every calculator and post that declares a dependency on it enters a review queue.
  4. The calculator’s formula version increments and the change appears in its changelog. Historic results computed under the previous version remain reproducible, because rulesets resolve by effective date rather than by wall-clock time.

What counts as wrong

A number that disagrees with a primary source. A convention applied without being stated. A degenerate input that produced a figure instead of an explanation. A page that claims more certainty than its method supports. All four are defects here, not just the first.