Area Converter
Convert area between square millimeters, square centimeters, square meters, hectares, square kilometers, square inches, square feet, square yards, acres, and square miles using exact squared conversion factors.
How It's Calculated
Formula
\text{result} = \text{value} \times \text{squareMetersPerFromUnit} \div \text{squareMetersPerToUnit}Area conversion means expressing the same two-dimensional extent in a different unit. Because area is length squared, every conversion factor here is itself a squared linear factor, not the plain linear factor used for length: 1 square foot equals (0.3048 m)² = 0.09290304 m², not 0.3048 m² — applying a linear factor only once to an area value is a common and incorrect shortcut. Every supported unit converts through one canonical base unit, the square meter: the input value is multiplied by its unit's square-meters-per-unit factor, then divided by the target unit's factor. Metric units (square millimeter, square centimeter, square meter, hectare, square kilometer) use exact powers of ten. US customary units (square inch, square foot, square yard, square mile) use the square of their exact linear meter equivalents. The acre is defined as exactly 43,560 square feet, giving it an exact square-meter equivalent as well.
Worked Examples
Metric to US: 1 hectare to acres
- Convert to square meters: 1 ha x 10,000 m² per ha = 10,000 m²
- Convert square meters to acres: 10,000 m² / 4046.8564224 m² per acre = 2.47105381... ac
- Result: 1 hectare is approximately 2.471054 acres
US to metric: 1 square foot to square meters
- Square the linear foot-to-meter factor: (0.3048 m)² = 0.09290304 m²
- 1 ft² x 0.09290304 m² per ft² = 0.09290304 m²
- Result: 1 square foot is exactly 0.09290304 square meters
Frequently Asked Questions
Why can't I just use the length conversion factor for area?
Area scales with the square of length, not linearly with it. Doubling both the width and height of a square quadruples its area, not just doubles it — so an area conversion factor must be the linear factor squared (e.g. feet-to-meters squared for square feet to square meters), never the plain linear factor applied once.
Is the acre defined independently, or derived from another unit?
The acre is defined as exactly 43,560 square feet, which in turn gives it an exact square-meter equivalent (43,560 x 0.09290304 m² per ft² = 4046.8564224 m² exactly) via the exact foot-to-meter definition — it is not an independently approximated constant.
Can I convert a negative area value?
Yes. This calculator treats area as a generic numeric quantity and converts negative values the same way as positive ones, consistent with how this project's other unit converters (length, weight) handle negative input.
What happens if I enter the same unit for both 'From' and 'To'?
The result equals the input value unchanged, since converting a unit to itself has a conversion factor of 1.