What this calculator does
Area units multiply two lengths together, so converting between them is not just a matter of looking up a single factor the way length conversion is: a square foot to square metre conversion uses the length factor squared, which is easy to get wrong by simply reusing the linear conversion.
This calculator handles that squaring internally, so entering an area in any unit, from a small workshop measurement in square centimetres up to farmland in square kilometres, converts correctly without needing to work the squaring out by hand.
The formula
Every area factor here is the corresponding length factor squared. A foot is 0.3048 m, so a square foot is 0.3048² = 0.092903 square metres: not 0.3048 square metres, a mistake that would understate a square-foot area by more than tenfold. Hectares and acres are land-specific units defined directly rather than derived from a squared length: a hectare is exactly 10,000 m², and an acre is 4,046.86 m², originally the area a team of oxen could plough in a day.
| Term | Meaning |
|---|---|
| Base unit | The square metre, which every other unit converts through. |
| Hectare | 10,000 square metres: the standard metric land unit. |
| Acre | 4,046.86 square metres, or about 0.405 hectares: the standard imperial land unit, historically tied to a day’s ploughing. |
The inputs explained
| Field | What to enter |
|---|---|
| Value | The value to convert. |
| From | The unit you are converting from. |
| To | The unit you want the answer in. |
When to use it
Converting a block or farm size between acres and hectares
Land is often listed in acres in older records or US contexts and hectares in metric ones: the two units convert at a fixed ratio of about 2.47 acres per hectare.
Checking floor area in square feet against a metric plan
Property listings in the US and UK often use square feet while plans and metric countries use square metres: a factor of roughly 10.76 square feet per square metre links the two.
Estimating material for flooring, turf or tiling
Whatever unit a quantity is quoted in, converting everything to the same unit before multiplying by a coverage rate avoids the most common estimating error in trade work.
Working with very small or very large areas
Square millimetres suit small components and technical drawings; square kilometres and square miles suit regions, catchments and countries: the same base-unit method spans the whole range.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
One of each unit, converted to square metres
A single unit of area from square millimetres to square miles, each converted to square metres to compare true scale.
| From | In square metres |
|---|---|
| Square millimetre | 0.000001 m2 |
| Square centimetre | 0.0001 m2 |
| Hectare | 10,000 m2 |
| Square kilometre | 1,000,000 m2 |
| Square inch | 0.00064516 m2 |
| Square foot | 0.092903 m2 |
| Square yard | 0.836127 m2 |
| Acre | 4,046.86 m2 |
Converting 500 square metres to other units
A 500 m² block or floor area expressed in each of the other common units.
| To | Result |
|---|---|
| Hectares | 0.05 ha |
| Square feet | 5,381.957526 ft2 |
| Square yards | 597.9952806 yd2 |
| Acres | 0.12355258 ac |
Questions
How do I convert square feet to square metres?
Multiply by 0.092903: the square of the length conversion factor 0.3048. This calculator applies that squared factor directly, so entering an area avoids the common mistake of reusing the plain length factor.
How many acres are in a hectare?
About 2.471 acres. A hectare is exactly 10,000 m², while an acre is 4,046.86 m², so the ratio is close to two and a half but not a clean round number, since the two units were defined independently.
Why can’t I just square the length conversion factor myself for any unit?
You can, and that is exactly what this calculator does internally: but hectares and acres are the exception, defined as fixed land-area units rather than derived by squaring a length, so they need their own separate factor.
How big is an acre in everyday terms?
About 4,047 m²: roughly three-quarters the size of a standard rugby pitch, or close to 40 tennis courts, and historically defined as the area one man with an ox team could plough in a day.
How do I convert a small technical area, like a cross-section in square millimetres?
Select square millimetres as the "from" unit and any target unit: the same base-unit method applies at the small end of the scale as at the large end, from mm² up to km².
For a single length rather than an area, see the length and distance converter. For volume, use the volume and capacity converter.