Convert square feet to square metres, acres to hectares and sq ft to Indian land units (guntha, cent, bigha, marla, kanal, ground), with exact factors.
1,000 ft² is exactly 92.90304 m². One square foot is exactly 0.09290304 m².
| Unit | Value | Definition |
|---|---|---|
| square metre (m²) | 92.90304 | Base unit |
| square kilometre (km²) | 0.00009290304 | 1 km² = 1,000,000 m², exact |
| square centimetre (cm²) | 929,030.4 | 1 cm² = 0.0001 m², exact |
| square millimetre (mm²) | 92,903,040 | 1 mm² = 0.000001 m², exact |
| hectare (ha) | 0.009290304 | 1 ha = 10,000 m², exact |
| are (a) | 0.9290304 | 1 a = 100 m², exact |
| acre (ac) | 0.02295684 | 1 ac = 4,046.8564224 m², exact |
| square foot (ft²) | 1,000 | 1 ft² = 0.09290304 m², exact |
| square inch (in²) | 144,000 | 1 in² = 0.00064516 m², exact |
| square yard (yd²) | 111.1111 | 1 yd² = 0.83612736 m², exact |
| square mile (mi²) | 0.00003587006 | 1 mi² = 2,589,988.110336 m², exact |
| cent | 2.295684 | 1 cent = 40.468564224 m², exact (India: 1/100 acre) |
| guntha | 0.9182736 | 1 guntha = 101.17141056 m², exact (India: 1/40 acre (1089 ft²)) |
| bigha (Uttar Pradesh) | 0.03673095 | 1 bigha = 2,529.285264 m², approximate (Varies by district; 27,225 ft² used here) |
| marla | 3.673095 | 1 marla = 25.29285264 m², exact (272.25 ft² (Punjab standard)) |
| kanal | 0.1836547 | 1 kanal = 505.8570528 m², exact (20 marla) |
| ground | 0.4166667 | 1 ground = 222.967296 m², exact (Tamil Nadu: 2400 ft²) |
1 ft² = 0.09290304 m², exact. Both units are defined exactly and the converted value is a terminating decimal, so every digit shown in it is exact.
An area unit is the square of a length unit, so its factor is the square of a length factor: 1 ft² = 0.3048² m² = 0.09290304 m² exactly. Every unit is held as a number of square metres, including the acre (43,560 ft²) and the hectare (10,000 m²), and a conversion multiplies by one factor and divides by the other.
Flat and plot sizes are the usual reason to convert. The default 1,000 ft² flat is 92.90304 m², and 1 hectare is 2.4711 acres. Indian land units are included: a guntha is 1/40 acre (1,089 ft²), a cent 1/100 acre (435.6 ft²) and a ground 2,400 ft².
The bigha has no national size. The converter uses 27,225 ft² and labels every result that involves it as approximate; the marla (272.25 ft²) and kanal (20 marla) follow the Punjab standard.
Checked against: 1 ft² = 0.3048² m² = 0.09290304 m² (NIST HB 44 App. C); Python 3.8 fractions from the legal definitions: 290322/3125
Checked against: NIST HB 44 App. C: 1 acre = 43,560 ft²
Checked against: 10,000 m² ÷ (43,560 × 0.09290304 m²) = 390625000/158080329 (Python 3.8 fractions from the legal definitions)
Checked against: 1 guntha = 1/40 acre = 43,560/40 ft² = 1,089 ft²
Exactly 43,560 ft². An acre was historically a strip one chain (66 ft) wide and one furlong (660 ft) long, and 66 × 660 = 43,560. With the international foot of 0.3048 m that is 4,046.8564224 m², or 0.4047 hectares.
2.4711 acres. A hectare is a 100 m × 100 m square, 10,000 m², and an acre is 4,046.8564224 m², so 10,000 ÷ 4,046.8564224 = 2.4710538 acres. In the other direction 1 acre is exactly 0.40468564224 ha.
Multiply by 0.09290304, or divide by 10.7639. The factor is 0.3048², the square of the metres in a foot, so it is exact. A 12 × 15 ft room (180 ft²) is 16.72 m²; multiplying by 0.3048 instead of its square would give 54.86, more than three times too much.
A guntha is 1,089 ft² (101.17 m²), a square 33 ft on each side and 1/40 of an acre. A cent is 1/100 acre, 435.6 ft² (40.47 m²). A ground is 2,400 ft² (222.97 m²). All three are fixed fractions of the acre or fixed square-foot areas, so their conversions are exact.
Each state, and sometimes each district, kept its own customary bigha. West Bengal and Assam use 14,400 ft² (1,600 sq yd); the pucca bigha of Rajasthan and the bigha of eastern Uttar Pradesh and Bihar are 27,225 ft² (3,025 sq yd); Himachal Pradesh uses 8,712 ft². This converter uses 27,225 ft², so check the local land record first.
Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 5 worked examples whose answers come from independent sources; for example, “1000 ft² to m²” is checked against 1 ft² = 0.3048² m² = 0.09290304 m² (NIST HB 44 App. C); Python 3.8 fractions from the legal definitions: 290322/3125.
NIST SP 811 (2008), Guide for the Use of the SI, Appendix B — conversion factors; NIST Handbook 44, Appendix C — General tables of units of measurement.
5 worked examples with independently sourced answers ship with this calculator. They run in the test suite; you can run them here too.
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