About the Area Converter

The area converter translates between metric and imperial units of area, including square millimetres, square centimetres, square metres, square kilometres, hectares, acres, square feet, square inches, square yards, and square miles. Whether you are measuring a property plot in acres, a floor plan in square feet, or a farm in hectares, this tool gives you an instant conversion in either direction.

Area units are squared versions of length units, so the conversion factors are the squares of the corresponding length factors. One square metre is not 100 square centimetres but 10000, because each side of the square is 100 centimetres and the area is 100 times 100. This squaring effect means that area conversions involve much larger or smaller numbers than the corresponding length conversions.

The hectare (10000 square metres) and the acre (about 4047 square metres) are the two most common units for measuring land area. The hectare is used in most of the world and is part of the metric system; the acre is used in the United States, the United Kingdom, and some other countries for real estate and agriculture.

How It Works

Each unit has a defined relationship to the square metre, the SI derived unit of area. The converter uses these factors to translate between any two units:

1 mm2  = 0.000001 m2     (1e-6)
1 cm2  = 0.0001 m2       (1e-4)
1 m2   = 1 m2
1 km2  = 1,000,000 m2    (1e6)
1 ha   = 10,000 m2       (1e4)
1 ac   = 4046.8564224 m2 (exact, 43560 square feet)
1 ft2  = 0.09290304 m2   (exact, 0.3048 squared)
1 in2  = 0.00064516 m2   (exact, 0.0254 squared)
1 yd2  = 0.83612736 m2   (exact, 0.9144 squared)
1 mi2  = 2,589,988.11 m2 (exact, 1609.344 squared)

Every conversion proceeds in two steps: the input is multiplied by the source unit's factor to give an area in square metres, then divided by the target unit's factor to give the result in the target unit. Because the factors are squares of the length factors, they are exact whenever the underlying length definition is exact.

The acre was originally defined as the area that a yoke of oxen could plough in one day, but it is now defined exactly as 43560 square feet, which equals approximately 4046.856 square metres. The hectare is defined exactly as 10000 square metres, making it a clean metric unit. One hectare equals approximately 2.471 acres.

Worked Examples

To convert 1 acre to square metres, the calculation is 1 * 4046.8564224 = 4046.86 square metres. To convert the same acre to hectares, the calculation is 4046.86 / 10000 = 0.4047 hectares, confirming the rough rule that one hectare is about 2.47 acres.

To convert 100 square feet to square metres, the calculation is 100 * 0.09290304 = 9.29 square metres. This is the area of a small room, and the conversion factor 0.0929 is widely used in real estate and interior design.

To convert 1 square mile to acres, the calculation is 2589988.11 / 4046.8564224 = 640 acres exactly, since one square mile is defined as 640 acres. This is why land in the United States is often surveyed in sections of 640 acres, each being one square mile.

When to Use This Tool

Use the area converter whenever you need to translate between area units:

Reading property listings that use acres, hectares, or square feet.
Converting floor plans between metric and imperial units.
Comparing land areas for agriculture or real estate.
Working with construction materials measured in square metres or square feet.
Calculating the coverage of paint, flooring, or roofing materials.
Interpreting surveying or mapping data from another country.
Teaching the relationships between metric and imperial area units.

Limitations & Disclaimer

This converter handles flat (two-dimensional) area only and does not convert surface area on a sphere, spherical excess, or three-dimensional volume. The acre is the international (US survey foot) acre; slightly different historical definitions exist. Very large or very small results may be displayed in scientific notation. For cadastral or legal surveys, verify with the appropriate authority. See our disclaimer for full details.

Frequently Asked Questions

Why is 1 square metre equal to 10000 square centimetres, not 100?

Because area is length times width, and both dimensions scale. A square metre is 100 centimetres on each side, so its area is 100 times 100, which is 10000 square centimetres. This squaring effect applies to all area conversions: the factor is the square of the corresponding length factor.

What is the difference between a hectare and an acre?

A hectare is 10000 square metres, part of the metric system, and is used in most of the world for land area. An acre is about 4047 square metres, an imperial unit used in the United States, the United Kingdom, and some other countries. One hectare equals approximately 2.471 acres.

Why is one square mile exactly 640 acres?

Because the acre was historically defined in terms of the square mile for land surveying purposes. The US Public Land Survey System divides land into sections of one square mile, each containing exactly 640 acres, which can be further subdivided into half-sections (320 acres) and quarter-sections (160 acres).

Are the conversions exact?

Yes. The metric-to-metric conversions are exact by definition. The imperial-to-metric conversions are exact because the underlying length definitions (inch, foot, yard, mile) were standardised in 1959 as exact multiples of the metre. The only source of error is floating-point rounding, which is negligible.

What unit should I use for my property?

It depends on your country. In most of the world, hectares or square metres are standard. In the United States, acres and square feet are used for land, and square feet for buildings. In the United Kingdom, both hectares and acres are used. Check local conventions before reporting an area.

How do I convert square kilometres to square miles?

Divide by approximately 2.59, or use the exact factor 2.589988. One square kilometre equals about 0.386 square miles, and one square mile equals about 2.59 square kilometres. The converter handles this calculation automatically through the square metre as an intermediate unit.

Last updated: July 21, 2026 · Author: HT99 Tools Editorial Team · Reviewed by: HT99 Tools Editorial Team