Calculator Disclaimer

The calculators, explanations, examples and other content on the site are provided for general information and education. They are designed to help you understand and estimate, not to tell you what to do.

A calculator can only work with the values you give it. An incorrect, mistyped or approximate input produces a result that is wrong in the same way, however carefully the calculation is done.

Every calculator also makes assumptions: a formula, a convention, a rounding rule or a default value. Each calculator page describes the assumptions it relies on, and our methodology explains the conventions shared across the site. If those assumptions do not match your situation, the result will not either.

We test calculators against known examples and edge cases, but we cannot guarantee that every result is correct for every input, or that a calculator is free of errors. Results are provided without any warranty, as set out in our Terms of Use.

Many calculations simplify the real world. A projection assumes a rate stays constant; a quantity estimate assumes regular shapes; a health measure describes a population average rather than an individual. Real outcomes depend on factors a calculator does not know, and they can differ from an estimate, sometimes significantly.

Displayed results are rounded to a sensible precision, as described in our methodology. A rounded figure is close to the exact value but not identical to it, and small differences can grow if you reuse a rounded result in further calculations. Where precision matters, carry full values through and round only at the end.

Calculators that depend on today's date, such as an age calculated "as of today", use the date on your device. If your device's date, time or time zone is set incorrectly, or you are near midnight in a different time zone from the person you are calculating for, the result can differ by a day. You can usually enter the date you want explicitly instead.

Calculators work in current web browsers. An outdated browser, a browser extension that changes pages, or automatic translation can occasionally interfere with how inputs are read or results are shown.

Calculator results are not financial, investment, medical, legal, tax, engineering, construction or other professional advice, and they do not replace advice from a qualified professional who knows your circumstances.

The right level of caution depends on the calculation:

• Everyday calculations, such as arithmetic or date differences, can usually be used as they are once you have checked your inputs.
• Money, tax and business results depend on rates, fees and rules that vary by country and change over time. Confirm figures with your provider, the relevant authority or a qualified adviser before you commit.
• Health and fitness results are general estimates, not a diagnosis or a treatment recommendation. Discuss health decisions with a doctor or other qualified health professional.
• Construction, engineering and vehicle results do not account for site conditions, building codes, safety margins or manufacturer specifications. Have important work checked by a qualified professional.

If a decision matters, treat a calculator result as a starting point. Check your inputs, read the assumptions on the calculator page, compare with another reliable method where possible, and take professional advice where the stakes justify it.

Some calculators rely on external information such as published rates, thresholds, regulations or technical standards. These change, and a calculator may not reflect a change immediately. Where a calculator depends on such information, check that it is still current before relying on the result.

Pages may cite or link to external sources. We choose them carefully, but we do not control them: their content, availability and accuracy can change after we link to them.

If you think a calculator gives a wrong result or a page contains an error, please tell us through the Contact page. Include the values you entered and the result you expected, so we can check and correct it.