Area Converter
Convert between m², acres, hectares, square feet, and Japanese units like tsubo and jo. Enter a value, pick a unit, and see every conversion at once.
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Input
Result
100 m² (Square meter) converted to square meters
100m²
| Unit | Symbol | Converted value |
|---|---|---|
| Square millimeter | mm² | 100,000,000 |
| Square centimeter | cm² | 1,000,000 |
| Square meter | m² | 100 |
| Square kilometer | km² | 0.0001 |
| Are | a | 1 |
| Hectare | ha | 0.01 |
| Tsubo | 坪 | 30.25 |
| Jo (tatami mat) | 畳 | 61.728395 |
| Square inch | in² | 155,000.310001 |
| Square foot | ft² | 1,076.391042 |
| Square mile | mi² | 3.8610e-5 |
| Acre | ac | 0.024711 |
| Tan | 反 | 0.100833 |
| Cho | 町 | 0.010083 |
How it works
- This tool converts between 14 area units: square millimeter (mm²), square centimeter (cm²), square meter (m²), square kilometer (km²), are (a), hectare (ha), tsubo, jo, square inch (in²), square foot (ft²), square mile (mi²), acre (ac), tan, and cho.
- The square meter (m²), the SI unit of area, is used as the base. Every input is first converted to square meters and then to the target unit, so any pair of units gives a consistent result.
- Japanese units are calculated as: 1 tsubo ≈ 3.305785 m², 1 jo = 1.62 m², 1 tan = 300 tsubo, and 1 cho = 3,000 tsubo. The acre uses the international acre (4046.8564224 m²).
- Just enter the area you want to convert and pick its unit. All conversions appear in the table, with the square meter value shown prominently as the headline figure.
- This is handy for comparing the tsubo, jo, tan, and cho units common in Japanese real estate and land records against metric and imperial units side by side.
- Decimals are rounded to a readable number of digits, and very large or very small values may switch to scientific notation. For contracts, registration, or other cases that demand exact figures, please double-check the source values.
Reading Japanese property listings
Apartment listings in Japan give the total floor area in square meters, but individual rooms are described in jo, the number of tatami mats that would fit. A listing for a 40.5 m² one-bedroom works out to about 436 sq ft. A "6-jo" bedroom, at the 1.62 m² per mat used here, is 9.72 m², or roughly 105 sq ft.
Land and building prices are often quoted per tsubo, about 3.3058 m² or 35.58 sq ft. To turn a price per tsubo into a price per square meter, multiply by 0.3025 (one tsubo is exactly 400/121 m²). A plot priced at 1,000,000 yen per tsubo is therefore 302,500 yen per m², or about 28,100 yen per sq ft.
Why tatami sizes differ
The 1.62 m² figure comes from the Japanese real-estate advertising code, which requires that a room advertised as a certain number of jo offer at least 1.62 m² per mat. Physical mats are not standardized, so the same "6-jo" label can describe noticeably different rooms:
- Kyoma (western Japan): 955 × 1910 mm, about 1.82 m²
- Chukyoma (Nagoya area): 910 × 1820 mm, about 1.66 m²
- Edoma (Tokyo area): 880 × 1760 mm, about 1.55 m²
- Danchima (public apartment blocks): 850 × 1700 mm, about 1.45 m²
Quick estimates and their error
A six-mat room is about 10.9 m² with Kyoma mats but only about 8.7 m² with Danchima mats, a gap of more than 2 m². When comparing apartments, use the square meter figure rather than the mat count. A few other rules of thumb:
- Square meters to square feet: multiply by 10.76. Multiplying by 10 is about 7 percent low; multiplying by 11 is about 2 percent high.
- Square feet to square meters: multiply by 0.0929, or divide by 10.76.
- One acre is exactly 43,560 sq ft, or about 4,047 m² (0.405 ha). One hectare is about 2.471 acres.
- One tsubo is roughly two tatami mats, but at 1.62 m² per mat two mats are about 2 percent smaller than a tsubo.
- One tan (about 991.7 m²) is close to 10 ares, and one cho (about 9,917 m²) is just under a hectare.
Common mistakes
The classic error is applying a length factor to an area. One meter is about 3.28 feet, but one square meter is 3.28 squared, about 10.76 sq ft. If you only know the dimensions of a room, convert each side first and then multiply, or multiply first and convert the area here.
Also check how an area was measured before comparing numbers. Japanese condominium brochures usually quote floor area measured to the center of the walls, while the land registry records the smaller area measured to the inside face of the walls. Other countries have their own conventions about whether walls, balconies or common areas are included, so two listings with the same number are not always the same size.
Frequently asked questions
- How does the area converter calculate its results?
- Every value is first converted into square meters (m², the SI base) and then into the target unit. Routing every conversion through m² keeps results consistent no matter which two units you compare.
- How big is one tsubo or one tatami (jō) in square meters?
- One tsubo is about 3.305785 m² and one tatami mat (jō) is defined here as 1.62 m². These traditional Japanese units appear alongside metric and imperial units like hectares and acres in the same table.
- Which acre definition does this tool use?
- It uses the international acre, exactly 4046.8564224 m². Because results are rounded for display, check the original figures for contracts or land registration where precision matters.
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