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Calculators for everyday questions

Work out a discount before buying, estimate how many tiles a room needs, or convert metres to feet. Browse a category or search for the calculation you need. There are 189 standalone formula calculators and 22,706 directional unit-conversion routes across 45 measurement subjects. The utility directory includes 148 operations and 896 regional formatting presets; presets share a formatting engine. Each formula calculator has a worked example. Conversion workspaces show their scale factors and live formulas.

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How do I use these calculators?

Open a tool, enter the numbers and check the units beside each input. Results update as you type. Use the reset button to return to the example values, or copy your result. Save frequently used tools with the star button; favourites are stored in this browser.

Are the calculators free?

Yes. All calculators and tools are free, and you do not need to create an account. Calculations run on your device. The site does not send your calculator inputs to an external calculation service.

How accurate are the results?

Results use standard JavaScript numeric arithmetic and display up to 12 significant digits. Rounding, measurement uncertainty and assumptions can affect the answer. Read the formula and limitations for your chosen tool. See our calculation methodology.