Area Converter

The SI derived unit of area is the square metre (m²). Larger SI units include the hectare (10,000 m²) and square kilometre (1,000,000 m²). The hectare is not formally an SI unit but is accepted for use with SI because of its practical importance in land measurement. US customary area units (square foot, acre, square mile) are derived from the inch: 1 ft² = 144 in², 1 acre = 43,560 ft², 1 mi² = 640 acres.

All conversions in this category are computed relative to a single base unit (Square Meter) using factors sourced from NIST Special Publication 811 and the BIPM SI Brochure. A shared reference unit keeps the conversion relationships consistent. Converting directly from the original measurement avoids the rounding differences that can accumulate when displayed intermediate results are entered again.

This calculator supports 10 units, including Square Meter, Square Kilometer, Square Centimeter, Square Millimeter, Hectare. Choose the unit shown in your source measurement, then the unit needed for your result.

Units may have alternate spellings or abbreviations. You can search using these names too. Examples include Square Meter (m2, also written as square meters or sq m), or Square Kilometer (km2, also written as square kilometers or sq km), or Square Centimeter (cm2, also written as square centimeters or sq cm).

All area conversions within the SI family are purely multiplicative: you multiply the source value by a fixed conversion factor derived from the ratio of the two unit definitions. Imperial-to-metric conversions use the exact defined equivalences (e.g., 1 inch = 25.4 mm exactly) rather than approximations.

When precision matters, avoid rounding intermediate calculations. The displayed factors and results are rounded for readability, usually to ten significant digits; very large or small values use scientific notation. Use the original measurement for each conversion and round the final answer to match the accuracy of that measurement.

Keep the unit alongside each area value when you copy or share it. Check that the source and target units match your task. If two units have similar names, read their definitions before selecting one.

For a second check, use the worked example and formula on the conversion page. Start from your original value rather than a rounded result from another calculator. If you need to report a specific number of decimal places, round once at the end.