Area Converter
Convert between square metres, square feet, acres, hectares, square miles and more.
How to use this calculator
- 1Enter the value you want to convert.
- 2Pick the unit you are converting from and the one you want.
- 3The table below shows the same value in every other supported unit.
How the calculation works
result = (value × factor(from) ) / factor(to)- factor
- How many square metres one unit represents
Every value is converted to square metres first, then out to the target unit. This means n units need n factors rather than n² conversion pairs.
Every factor here is the square of the corresponding length factor, and since the inch (0.0254 m) and yard (0.9144 m) are exact legal definitions, so are all the imperial area factors derived from them.
The acre is defined as exactly 4,840 square yards — historically the area a yoke of oxen could plough in a day, which is why it is not a round number in any modern unit.
Because area scales with the square of length, a doubling of linear size quadruples the area. This trips people up constantly: a 20 ft × 20 ft room is four times the floor area of a 10 ft × 10 ft one, not twice.
Worked example
1 acre to hectare
- 1.One acre is 4,046.8564 square metres, so 1 ac is 4,046.8564 square metres.
- 2.One hectare is 10,000 square metres, so divide: 4,046.8564 ÷ 10,000 = 0.4046856.
- 3.Put another way, 1 ac = 0.4046856 ha.
Result: 0.4046856 ha
Why area units are squared length units
Every unit of area is derived from a unit of length by squaring it — a square metre is the area of a square one metre on each side. That means area conversion factors are always the square of the corresponding length factor: one foot is 0.3048 metres, so one square foot is 0.3048², or 0.09290304 square metres. Because the international definitions of the inch, foot and yard are exact, every imperial area factor derived from them is exact too.
The squaring relationship has a consequence people routinely get wrong when scaling estimates: a room twice as long and twice as wide has four times the floor area, not twice. Underestimating this is one of the most common sources of material shortfalls in flooring, paint and landscaping jobs.
The land units that refuse to be tidy
Land measurement kept its own units long after most other trades standardised, and those units carry their history openly.
- Acre — defined as exactly 4,840 square yards, but originally the area a yoke of oxen could plough in one day — a rectangle one furlong long by one chain wide. That agricultural origin is why it converts to no round figure in metric.
- Hectare — the metric answer, defined as exactly 10,000 square metres (a square 100 m on a side). Deliberately sized to be comparable to an acre while remaining a clean power of ten.
- Square mile and section — a square mile is exactly 640 acres, a relationship built into the US Public Land Survey System, where a "section" of surveyed land is one square mile.
Choosing the right unit for the job
The practical rule is to pick the unit that keeps the number in a readable range without scientific notation. Square millimetres and square inches suit component and material specifications; square metres and square feet suit rooms, floors and buildings; acres and hectares suit fields, plots and parkland; square kilometres and square miles suit regions and countries. Converting a national land area into square feet is arithmetically valid and completely useless — which is the real reason so many area units continue to coexist.
What this assumes, and where it stops
Assumptions
- Conversion factors follow the internationally agreed definitions of each unit.
Limitations
- Results are computed in double-precision floating point, which is exact to about 15 significant figures.
- Very large or very small values are displayed in scientific notation to avoid misleading precision.
Common questions
How many acres are in a hectare?
One hectare is about 2.471 acres, and one acre is about 0.405 hectares. A hectare is a round 10,000 square metres by definition, while an acre is 4,840 square yards, so neither converts to a tidy number in the other system.
Why is doubling a room's dimensions more than doubling its area?
Because area is a squared quantity. Doubling both the length and the width multiplies the area by four, not two. This is the single most common error when scaling up flooring, paint or land estimates from a smaller reference.
Formula and content last reviewed on .
Results are estimates for information only, not professional advice.
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