Area Converter
Convert area between metric and imperial units instantly, from square millimetres to square miles.
What this tool does
To convert area, multiply by the exact factor between the two units - for example, 1 acre is exactly 4,046.8564224 square metres, and 1 hectare is exactly 10,000 square metres. This tool converts between ten units at once - square millimetres up to square kilometres, plus square inches, feet, yards and miles, hectares and acres - and shows the exact factor alongside the result.
Converts area between ten metric and imperial units - square millimetres, centimetres, metres, kilometres, hectares, and square inches, feet, yards, miles and acres.
Shows the exact conversion factor used, not just the answer.
Uses the already-squared factor directly, avoiding the classic mistake of applying an un-squared length factor to an area conversion.
How to use it
- Enter the area you want to convert.
- Pick the unit you're converting from and the unit you're converting to.
- Read the result, or press Swap units to reverse it.
Why use this converter
Land, floors and rooms are measured in square metres, square feet, acres and hectares, and the factors are the squares of length factors, which people forget. A direct converter uses the correct area factor every time.
Why we built it
We built the area converter to use the already-squared factors directly, avoiding the classic mistake of applying a length factor to an area. For common pairs see the square feet to square metres converter and the acres to hectares converter.
For a neighbouring job there is also the Tile Calculator.
Who this tool is for
- Home buyers and renters comparing property sizes
- Farmers and gardeners
- Students
When to use it
- Reading property or land listings from another country.
- Estimating flooring, paint or turf coverage.
- Comparing farm, park or garden sizes.
- Converting planning or school measurement problems.
Area units are length units squared - which is where errors creep in
You can't just square the length conversion factor by eye.
Every area unit is built by squaring a length unit: a square metre is 1 metre by 1 metre, a square foot is 1 foot by 1 foot. So converting area between systems means squaring the length conversion factor, not just carrying it over - since 1 foot is 0.3048 metres, 1 square foot is 0.3048 squared, or 0.09290304 square metres, not 0.3048 square metres. Applying the un-squared length factor straight to an area figure is the classic area-conversion mistake, and this tool uses the already-squared factor directly, avoiding it entirely.
Acres and hectares aren't multiples of a smaller unit
Unlike square metres or square feet, an acre and a hectare aren't simply a length unit squared - both are historical land-measurement units with their own independent definitions. A hectare is defined as exactly 10,000 square metres (a 100 m by 100 m square). An acre comes from an older English unit - originally the area a team of oxen could plough in a day - and is fixed today at exactly 4,046.8564224 square metres, or 43,560 square feet. One square mile is exactly 640 acres, which is why acre and square-mile figures convert to clean round numbers between each other even though the metric conversion looks less tidy.
What you give it, and what you get back
| Item | Details |
|---|---|
| Value | An area in the "from" unit. |
| From and To | Square millimetres to square miles, plus hectares and acres. |
| Output | The converted area and the exact factor. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| Result is far too small or large | A length factor was applied to an area. | Use this converter - it applies the squared factor. |
| Acres vs hectares confusion | One hectare is about 2.471 acres. | Check which unit the listing uses. |
| Local land units | Regional units are not included. | Convert through a standard unit if you know the local definition. |
Assumptions and limitations
- This converts area (two-dimensional) units only - for volume (three-dimensional, cubic units), use the dedicated volume converter.
- Land area conventions can vary locally (some regions use non-standard local units for land, like the Filipino hectare-adjacent 'ektarya' variants); this tool covers the standard international units.
- Very large or very small results are shown with practical rounding for readability; the internal calculation is exact.
Frequently asked questions
How many square metres are in an acre?
Exactly 4,046.8564224 square metres. An acre is a historical land unit, not a squared metric length, which is why the figure doesn't round to anything tidier.
How many square feet are in an acre?
Exactly 43,560 square feet. This is one of the cleaner conversions involving an acre, since the acre was historically related to English units like the furlong and chain that also relate cleanly to the foot.
How many acres are in a hectare?
About 2.471 acres. A hectare (10,000 m²) and an acre (4,046.8564224 m²) come from entirely separate historical definitions, so the conversion factor between them isn't a round number.
How do I convert square feet to square metres?
Multiply by 0.09290304, which is the length factor (0.3048 m per foot) squared. Squaring the length factor - rather than using the length factor directly - is the step that trips people up when converting area by hand.
How many acres are in a square mile?
Exactly 640 acres. This is a clean, defined relationship, unlike the metric conversions for either unit, since both trace back to the same historical English land-measurement system.
Are these area conversion factors exact?
Yes. The hectare (10,000 m²), the acre (4,046.8564224 m²) and every squared-length unit here (square foot, square inch, and so on) use internationally defined exact constants, not measured or rounded approximations.
Sources and accuracy
Exact internationally defined constants: the hectare (10,000 sq m) and acre (4046.8564224 sq m) per their legal land-measurement definitions.
Figures last checked against the source on . Standards and rates can change — if you are relying on this for something that matters, confirm against the source above. Think a figure is wrong or out of date? Send a correction.