Area Converter
Type a number once — see it in every area unit instantly.
Enter a number to see it in every unit.
All units at once
| Unit | Value |
|---|---|
| Square millimeter (mm²) | — |
| Square centimeter (cm²) | — |
| Square meter (m²) | — |
| Square kilometer (km²) | — |
| Hectare (ha) | — |
| Square inch (in²) | — |
| Square foot (ft²) | — |
| Square yard (yd²) | — |
| Acre (ac) | — |
| Square mile (mi²) | — |
| Pyeong (평) | — |
Why area conversion trips people up
Area units don't scale the way people expect from everyday length conversions, because area is a squared quantity. A property listed in square feet, a farm plot measured in acres, and a Korean apartment quoted in pyeong (평) all describe the same kind of thing — surface area — but the units come from three unrelated systems (imperial, US survey/English land measure, and the traditional Korean unit still used in real estate). This converter exists for the moment you need to compare them: reading an overseas listing, sizing flooring or turf for a room, or checking whether a plot described in hectares matches what a broker quoted in pyeong.
How to use it
- Enter the number you have — for example the floor area on a listing, or the acreage on a deed.
- Set From to the unit that number is already in, and To to the unit you want. The swap button (⇄) flips both at once.
- Read the highlighted result, or scroll the table below to see the same value expressed in all ten units simultaneously.
The math: why you can't just square a length factor casually
Every conversion here goes through square meters as the common base. A linear factor is squared to get the matching area factor — but you square the exact linear ratio, not a rounded one. A foot is defined as exactly 0.3048 m, so a square foot is 0.3048² = 0.09290304 m² exactly (not the rough 0.093 many people memorize). A yard is 3 ft, so a square yard is 9 × that factor, 0.83612736 m². Pyeong is defined as 400⁄121 m² (≈3.305785 m²), a ratio that comes from the historical conversion of the Japanese/Korean 尺貫法 (shakkanhō) unit "tsubo" into the metric system — it is not a round number in either direction, which is why hand-converting it by memory tends to drift over large areas.
Worked examples
Reference: exact conversion factors to 1 m²
| Unit | 1 unit in m² | Typical use |
|---|---|---|
| Square millimeter (mm²) | 0.000001 | Precision machining, PCB traces |
| Square centimeter (cm²) | 0.0001 | Small parts, fabric swatches |
| Square meter (m²) | 1 (base) | Floor area, most of the world |
| Square kilometer (km²) | 1,000,000 | Cities, regions, watersheds |
| Hectare (ha) | 10,000 | Farmland, forestry (metric world) |
| Square inch (in²) | 0.00064516 | Screens, small US/UK parts |
| Square foot (ft²) | 0.09290304 | US/UK real estate, flooring |
| Square yard (yd²) | 0.83612736 | Carpet, turf, US construction |
| Acre (ac) | 4046.8564224 | Farmland, land deeds (US/UK) |
| Pyeong (평) | 3.305785… (400⁄121) | Korean apartments & land |
Common mistakes
- Squaring the wrong factor. Multiplying an area in ft² by the linear factor 0.3048 (instead of 0.09290304) undercounts by roughly a factor of 3.28 — a very common spreadsheet error.
- Rounding pyeong to "3.3 m²". Fine for a single room, but on a large plot the rounding error compounds — use the exact 400⁄121 ratio this tool applies.
- Treating acres and hectares as interchangeable. They're close in magnitude (1 ha ≈ 2.47 ac) but not equal — mixing them up on a land deed or purchase agreement is a real, expensive mistake.
- Confusing gross vs. exclusive floor area. Korean real estate distinguishes 전용면적 (exclusive/private area) from 공급면적 (supply area including shared space); this converter only converts the number you type, not which definition it represents — check which figure a listing is quoting before converting.
What this tool doesn't do
This is a unit converter, not a geometry calculator — it doesn't compute area from a length × width you haven't multiplied yet, and it can't tell you which floor-area definition a listing used. For legal or contractual purposes (land deeds, permits, tax filings), always convert from the exact figure stated in the original document, and confirm the unit convention your jurisdiction expects.
Sources & further reading
- NIST Office of Weights and Measures — official U.S. definitions and conversion factors for length and area units
- NIST SP 811 — Guide for the Use of the SI, including exact metric–customary conversion factors
- USDA National Agricultural Statistics Service — land area reported in acres for U.S. farmland
Frequently asked questions
How many square feet are in a square meter?
One square meter equals about 10.7639 square feet, and 1 square foot equals exactly 0.09290304 m². That factor is exact because a foot is exactly 0.3048 m, so a square foot is 0.3048² m². To go from sq ft to sq m, multiply by 0.09290304; to go the other way, divide by it. For example 100 ft² = 9.290304 m² and 50 m² ≈ 538.2 ft².
How do acres and hectares compare?
1 acre = 4046.8564224 m² and 1 hectare = 10,000 m² exactly, so 1 ha ≈ 2.4711 acres and 1 acre ≈ 0.4047 ha. Acres are common for land and farm plots in the US and UK, while hectares are the metric standard used almost everywhere else. Type a plot size once here and read it in both acres and hectares at the same time.
What is 평 (pyeong)?
Pyeong (평) is the traditional Korean unit for floor area and land, still used for apartments and real estate. One pyeong equals 400/121 ≈ 3.3058 m² (about 35.58 ft²). So a 84 m² apartment is roughly 25.4 pyeong. This converter includes pyeong alongside the metric and imperial units so Korean listings and global units line up instantly.
How precise are the results?
Every conversion keeps up to 10 significant figures, then trims trailing zeros for readability. Very large or very small numbers (roughly 1e15 and above, or below 1e-9) switch to scientific notation, so nothing is silently rounded away to zero. All values come from the exact definition of each area unit — for example the square foot is exactly 0.09290304 m².
Is my input sent to a server?
No. This area converter runs entirely in your browser — the number you type is never uploaded anywhere. The only thing saved is your last chosen unit pair (for example square feet → square meters), kept in your browser's local storage so it is ready next time. The value itself is not stored.