How to use the Area Converter
- Enter the area figure from your plan, deed or listing.
- Choose its current unit and the unit you need.
- For a rectangular space, multiply the two dimensions first and convert the product.
- Compare the alternate units shown to sanity-check an unfamiliar figure.
- Add a waste allowance separately when the area feeds a material order.
How the calculation works
Area units convert through the square metre, and the crucial point is that the factor is the square of the length factor, not the length factor itself. One foot is 0.3048 m, so one square foot is 0.3048² = 0.09290304 m². Forgetting to square is the single most common conversion error in construction estimating, and it produces an answer wrong by a factor of three, which is large enough to be caught — unlike the subtler errors it sits beside.
The acre is a medieval survival, originally the area a yoke of oxen could plough in a day, now fixed at exactly 43,560 square feet or 4,046.86 m². Its awkwardness is historical: it was defined as one chain by one furlong, a strip 22 yards wide and 220 yards long. The hectare, at 10,000 m², was invented as a rational replacement and is roughly 2.471 acres.
Property listings routinely mix conventions, and the mixing is not always innocent. Gross internal area, net internal area and gross external area can differ by 10 to 20% for the same building depending on how walls, stairwells and plant rooms are treated. Convert the units first, then confirm which measurement standard produced the figure, because unit conversion cannot rescue a definitional mismatch.
area_target = (area_source × m²_per_source) ÷ m²_per_target; ft² = 0.09290304 m²; acre = 4046.8564224 m²; hectare = 10,000 m²Source: International Yard and Pound Agreement (1959); NIST Special Publication 811; RICS Property Measurement, 2nd edition.
Worked example
A plot is advertised at 0.75 acres and you want to know whether it takes a 250 m² footprint plus garden.
- Enter 0.75 and select acres.
- Convert to square metres: 0.75 × 4,046.86 = 3,035 m².
- Subtract the building footprint: 3,035 − 250 = 2,785 m² remaining.
- For a feel, that is about 0.28 hectares of garden, or roughly 30,000 ft².
0.75 acres is 3,035 m², so a 250 m² house occupies only about 8% of the plot.
Frequently asked questions
How many square feet in an acre?+
Exactly 43,560. It is a defined figure, derived from one chain by one furlong.
Why can't I just convert feet to metres and use the same number?+
Because area is two-dimensional. You must square the length factor: 1 ft² is 0.0929 m², not 0.3048 m².
How big is a hectare?+
10,000 m², a square 100 m on each side, or about 2.47 acres. It is roughly one and a half football pitches.
Does this work for irregular plots?+
Split an irregular plot into rectangles and triangles, total the areas in one unit, then convert the total. The acreage calculator handles common plot shapes directly.
Last reviewed September 1, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.