Area unit reference table
Exact square-meters equivalents for every unit supported by this converter.
| Unit | Symbol | Square meters equivalent |
|---|---|---|
| Square meter | m² | 1 m² |
| Square kilometer | km² | 1,000,000 m² |
| Square foot | ft² | 0.09290304 m² |
| Acre | acre | 4,046.8564224 m² |
| Hectare | ha | 10,000 m² |
- 1 hectare ≈ 2.471 acres — a frequent source of confusion when comparing land listings across countries that use one unit or the other.
- This converter uses the international-foot acre (4,046.8564224 m²); the historical US survey acre differs by only a few parts per million and is no longer standard practice.
- Area scales with the square of length, so a linear length-conversion factor must never be applied directly to an area value.
How are area units defined?
Area units derive from squaring an underlying length unit. The square meter (m²) is the SI coherent unit of area; the square foot (ft²) follows exactly from the defined international foot (0.3048 m), so 1 ft² equals exactly 0.3048² = 0.09290304 m². The hectare is a non-SI unit accepted for use with the SI, defined as exactly 10,000 m² (a 100 m × 100 m square), and is the standard unit for land area across most of the world.
The acre is an older customary unit of land area with roots in medieval English agriculture (traditionally the area a yoke of oxen could plough in a day), later standardized for legal and survey purposes. Using the international foot, it is now defined as exactly 4,046.8564224 m² (equivalently, 43,560 international square feet). A very slightly different "US survey acre," based on the historical US survey foot, existed for legal land-survey work in parts of the US; NIST and the National Geodetic Survey retired the underlying survey foot at the end of 2022, and this converter uses the standard international-foot acre throughout.
How to use this area converter
- Enter the area value you want to convert.
- Select the unit that value is currently in — square meters, square kilometers, square feet, acres or hectares.
- Read the converted results across the other four units, shown at once.
- For rough land-size intuition, remember 1 hectare ≈ 2.47 acres and 1 acre ≈ 4,047 m² (roughly two-thirds of a soccer pitch).
The formula behind area conversion
Every input value is first converted to square meters using its exact factor, then re-expressed in each other unit by dividing by that unit's own square-meters equivalent. Because area scales with the square of a length factor, area conversion factors are the square of the corresponding length factors, not the length factors themselves.
Common mistakes
- Confusing acres and hectares — 1 hectare is about 2.47 acres, so treating the two as roughly equal misjudges land size by more than double.
- Applying a linear length conversion factor to an area figure, for example multiplying a square-foot value by the feet-to-meters factor instead of its square.
- Forgetting that doubling a plot's side length quadruples its area rather than doubling it, since area scales with the square of linear dimensions.
- Mixing the historical US survey acre/foot with the standard international-foot acre this converter uses — the difference is tiny (a few parts per million) but was tracked separately in US land records until the US survey foot's retirement in 2022.
Domande frequenti
How many square meters are in an acre?
One acre equals exactly 4,046.8564224 square meters, or equivalently 43,560 square feet, using the international foot (0.3048 m). It is a customary land-area unit still widely used for real estate and agriculture in the US, UK and several other countries.
How many acres are in a hectare?
One hectare equals approximately 2.471 acres. Since a hectare is defined as exactly 10,000 square meters and an acre as exactly 4,046.8564224 square meters, dividing gives 10,000 ÷ 4,046.8564224 ≈ 2.4711.
How do you convert square feet to square meters?
Multiply the square-foot value by 0.09290304, the exact square of the international foot's meter-equivalent (0.3048² m²). For example, 1,000 ft² converts to 1,000 × 0.09290304 ≈ 92.9 m².
Why can't I just use the length conversion factor for area?
Because area is a two-dimensional (squared) quantity. Converting a length by a factor of, say, 0.3048 (feet to meters) requires squaring that factor — 0.3048² = 0.09290304 — to convert the corresponding area correctly. Using the linear factor directly understates the correct area conversion.
What is a hectare used for?
The hectare (exactly 10,000 m², or 100 m × 100 m) is the standard unit for measuring land area in most countries outside the US, commonly used for farmland, forestry and urban planning. It is a non-SI unit formally accepted for continued use alongside SI units by the International Bureau of Weights and Measures.
Fonti
- National Institute of Standards and Technology (NIST). Special Publication 811: Guide for the Use of the International System of Units (SI), 2008 Edition.
- International Bureau of Weights and Measures (BIPM). The International System of Units (SI Brochure), 9th edition, 2019 — hectare as a non-SI unit accepted for use with SI.
- NIST Handbook 44, Appendix C: General Tables of Units of Measurement (acre and square-foot definitions).
- NIST / National Geodetic Survey. Notice on the retirement of the U.S. survey foot, effective December 31, 2022.