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Found a formula issue, an outdated assumption, a broken link, or an explanation that could be clearer? Want a calculator we do not have yet? Send a message and we will reply by email.

How corrections work

  1. Tell us the calculator, the values you entered, and what you expected.
  2. We recheck the formula and its sources, and rerun the worked example.
  3. If something is wrong, we fix it, update the page’s review date, and reply to let you know.

Our methodology explains how formulas, defaults, and rounding are chosen.

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