The square trap: length factors do not work for area
The most common area mistake is multiplying by the length factor. One foot is exactly 0.3048 metres — but one square foot is not 0.3048 square metres. A square foot is a foot times a foot, so the factor is 0.3048 × 0.3048 = 0.09290304 square metres. Anyone converting with the unsquared factor gets an answer more than three times too big. This converter keeps that trap shut by converting every unit through square metres with the exact international definitions — the same foot the world agreed on in 1959.
The factors, with every variable defined
Step 1 — into square metres: m² = value × the from-unit's m²Step 2 — out to the target: result = m² ÷ the to-unit's m²m² per unit: sq mm 0.000001 · sq cm 0.0001 · sq m 1 · hectare 10,000 · sq km 1,000,000 · sq in 0.00064516 · sq ft 0.09290304 · sq yd 0.83612736 · acre 4,046.8564224 · sq mi 2,589,988.110336The acre rule: 1 acre = 4,840 sq yd = 43,560 sq ft, exactly
The imperial factors all descend from one definition — the international foot of exactly 0.3048 metres. Square it for the square foot (0.09290304), multiply by 144 for the square inch (0.00064516), by 9 for the square yard (0.83612736). The acre is a medieval survivor defined as 4,840 square yards, which is why it lands on the odd figure of 4,046.8564224 square metres; the square mile is 640 acres exactly, and the hectare is the tidy metric invention — 10,000 square metres, no history attached.
Worked example, done step by step
Convert 1 acre to hectares — the land-listing question. Step 1: into square metres. 1 × 4,046.8564224 = 4,046.86 m². Step 2: out to hectares. 4,046.86 ÷ 10,000 = 0.4047 hectares. The same acre is 43,560 sq ft and 1/640 of a square mile — all ten units sit in the every-unit table the moment you type.
The house example — 2,000 sq ft. A 2,000 sq ft American house is 2,000 × 0.09290304 = 185.81 m². Run it backwards and the common European listing of 100 m² is 100 ÷ 0.09290304 = 1,076.39 sq ft. Flat and room listings swap countries constantly; this is the arithmetic underneath every one of those conversions.
Plots you know, in every unit
| Plot | Square feet | Square metres | Acres / hectares |
|---|---|---|---|
| A 30 × 40 ft plot | 1,200 | 111.48 | 0.0275 ac |
| A quarter-acre suburban lot | 10,890 | 1,011.71 | 0.25 ac |
| 1 acre (worked example) | 43,560 | 4,046.86 | 0.4047 ha |
| 1 hectare | 107,639.1 | 10,000 | 2.4711 ac |
The ratio between any two columns never changes: every decimal hectare is 2.47105 acres, every square foot is 0.09290304 square metres. That fixed ratio is why the chart above can draw four wildly different plots on one scale — only the labels change, never the arithmetic.
Reading the result, and its limits
Three honest notes. First, the acre in old American records can differ in the last decimals: until the end of 2022 the US kept a second, slightly longer survey foot, and the standards body retired it in favour of the international foot on 1 January 2023. A survey-foot acre is about 0.17 square feet larger — meaningless for a house plot, worth knowing for a section of farmland. This page uses international feet throughout. Second, rounding: the page displays two decimals, which is plenty for buying and renting decisions; the square-metre figures underneath are exact. Third, this page converts areas you already have — if you need the area itself from a shape's dimensions, the square footage calculator measures rectangles, circles, triangles and trapezoids first, and the flooring calculator turns a room's area into the boxes you actually buy.
Frequently asked questions
How many square feet are in an acre?
43,560 square feet, exactly — one acre is 4,840 square yards, and the figure never varies. It is also 4,046.86 square metres and 0.4047 hectares. A handy mental image: an acre is roughly the size of an American football field without the end zones.
How do I convert square feet to square metres?
Multiply square feet by 0.09290304. The trap to avoid is multiplying by 0.3048, which is the factor for lengths, not areas — a square foot is a foot times a foot, so the factor must be 0.3048 × 0.3048. Example: 1,000 sq ft × 0.09290304 = 92.9 m². The converter above does it instantly.
What is the difference between an acre and a hectare?
They are both land units from different systems: an acre is imperial (43,560 sq ft = 4,046.86 m²) and a hectare is metric (exactly 10,000 m²). One hectare equals 2.47105 acres, so a hectare is about two and a half times an acre. The US measures land in acres; most of the rest of the world uses hectares.
Why is multiplying by 0.3048 wrong for area?
Because 0.3048 converts a length, and area is length × length. Converting 1,000 sq ft with the length factor gives 304.8 m² — more than three times the true 92.9 m². The correct factor is 0.3048 squared: 0.09290304. Every conversion on this page squares the trap shut by routing through square metres.
