Most of the world records land officially in square meters, hectares, or acres, yet a great deal of land is still bought, sold, inherited, and talked about in older units: the bigha in northern India, the rai in Thailand, the tsubo in Japan, the feddan in Egypt. Some of these units now have one exact legal size. Others change from one state, district, or even village to the next, so a single conversion found online can be badly wrong. This guide tours the main regions, gives exact values where a unit is standardized, and points to our unit pages for the ones that vary.
One rule applies everywhere: the official land record decides. If a deed, title, or revenue record states an area, the definition used by the issuing office is the one that counts. Use any conversion, including ours, as a check, not as a substitute.
Fixed units and variable units
A unit is standardized when law or long-settled practice gives it one exact size wherever it is used. The Thai rai, the Japanese tsubo, and the Indian guntha and cent fall into this group, and converting them is simple arithmetic.
A unit is variable when the same name covers different sizes. The bigha is the classic example. Its size depends on the state, sometimes the district, and sometimes on which of several local systems a document follows. For these units, the first job is to find out which definition applies, and only then to convert.
The comparison below shows some fixed-size units at the same scale.
South Asia
South Asia has the richest mix of land units, and also the most variation. India records land in hectares, acres, or square meters in many states’ official records, but sale deeds, local revenue offices, and everyday conversation often use traditional units.
Bigha. Used across northern and eastern India, Nepal, and Bangladesh. Its size varies widely between states and sometimes between districts. It is usually divided into smaller units such as the katha or the biswa, but how many of each make a bigha also differs by region. Never convert a bigha without knowing where the land is. The bigha and katha pages list regional values.
Kanal and marla. Used in the Punjab region of India and Pakistan and in neighboring areas. One kanal is 20 marla, but the marla itself is not one size: the square footage used for a marla differs between regions, and in Pakistan housing schemes can follow a different figure from the revenue records. See the kanal and marla pages.
Guntha. Used in Maharashtra, Karnataka, Gujarat, Telangana, and Andhra Pradesh. It is fixed at 33 ft × 33 ft, which is 1,089 sq ft (about 101.17 m²). Forty guntha make exactly one acre. See the guntha page.
Cent. Common in Kerala, Tamil Nadu, Karnataka, and Andhra Pradesh. One cent is one hundredth of an acre: 435.6 sq ft, or about 40.47 m².
Ground. Used for urban plots in Tamil Nadu, especially Chennai. One ground is 2,400 sq ft, about 222.97 m², or roughly 5.5 cents.
| Unit | Where | Size |
|---|---|---|
| Guntha | Western and southern India | 1,089 sq ft ≈ 101.17 m² (1/40 acre) |
| Cent | Southern India | 435.6 sq ft ≈ 40.47 m² (1/100 acre) |
| Ground | Tamil Nadu | 2,400 sq ft ≈ 222.97 m² |
| Bigha, katha, biswa | North and east India, Nepal, Bangladesh | Varies by region |
| Kanal, marla | Punjab region (India and Pakistan) | 1 kanal = 20 marla; marla size varies |
Southeast Asia
Thailand: rai, ngan, and square wah. Thai land titles state area in three parts: rai, ngan, and square wah (tarang wa). The system is fixed and metric-based:
- 1 square wah = 4 m² (a wah is 2 m)
- 1 ngan = 100 square wah = 400 m²
- 1 rai = 4 ngan = 1,600 m²
So 1 hectare is exactly 6.25 rai, and 1 acre is about 2.53 rai. Areas are often written as three numbers, so “2-1-50” means 2 rai, 1 ngan, 50 square wah: 3,200 + 400 + 200 = 3,800 m², or about 0.94 acre. See the rai page.
East Asia
Japan: tsubo. One tsubo is exactly 400/121 m², about 3.306 m² or 35.58 sq ft, and is often pictured as roughly two tatami mats. Official documents in Japan use square meters, but tsubo remain common when people discuss house plots and floor space. 1,000 m² is 302.5 tsubo. See the tsubo page.
Korea: pyeong. The pyeong has the same size as the tsubo, 400/121 m². South Korea moved official measurement to square meters, but pyeong is still widely used in conversation, especially for apartment sizes. A “30-pyeong” apartment is about 99.2 m². See the pyeong page.
China: mu. In mainland China one mu is defined as one fifteenth of a hectare, about 666.67 m², so 15 mu make exactly 1 hectare and an acre is about 6.07 mu. The mu is still standard in talk about farmland. See the mu page.
Middle East and North Africa
Feddan. The main land unit in Egypt, also used in Sudan. In Egypt one feddan is 4,200 m², made up of 24 qirat of 175 m² each. That is about 1.04 acres, so a feddan and an acre are close but not interchangeable. See the feddan page.
Dunam (dönüm). A unit inherited from the Ottoman Empire and still used in Turkey, Israel, the Palestinian territories, Jordan, and other parts of the region. The modern metric dunam is 1,000 m², a tenth of a hectare, or about 0.247 acre. Older and local dunams of other sizes appear in some countries and in historical records, so check which one a document means. See the dunam page.
Europe and Africa
Continental Europe uses the hectare and the are (100 m²) almost everywhere, but older units still appear in historical deeds.
Morgen. Originally the area a team could plow in a morning, the morgen was used in German-speaking regions and the Netherlands and was carried to South Africa, where it still appears in older title deeds. Its size differed considerably from one region and period to another, so it must be converted with the right local definition. See the morgen page.
The Americas
Arpent. A French unit used for both length and area, still found in Quebec and Louisiana, mainly in older property descriptions. As an area, the common French arpent is about 0.85 acre, but variants exist. See the arpent page.
Manzana. Used for farmland in much of Central America. It is defined as 10,000 square varas, and because the length of the vara differs slightly between countries, the manzana is roughly 0.7 hectare with country-specific values. Check the national definition before converting.
Cuerda. Used in Puerto Rico, where one cuerda is about 3,930 m², or about 0.97 acre. It is close enough to an acre to be confused with one, and different enough to matter on a large parcel.
English and US survey units
The acre itself grew out of a family of older English units, several of which survive in deeds, survey plats, and some countries’ everyday usage.
| Unit | Definition | Size |
|---|---|---|
| Perch (square rod) | 16.5 ft × 16.5 ft | 272.25 sq ft ≈ 25.29 m²; 160 per acre |
| Rood | 1/4 acre = 40 perches | 10,890 sq ft ≈ 1,011.7 m² |
| Square chain | 66 ft × 66 ft | 4,356 sq ft; 10 per acre |
| Section | 1 mile × 1 mile | 640 acres |
| Township | 6 miles × 6 miles = 36 sections | 23,040 acres |
Rood and perch. Older deeds in Britain and Ireland describe land in acres, roods, and perches, sometimes written “A-R-P”. The system is still in everyday use in Sri Lanka, where small plots are often sold by the perch. A plot of “1A 2R 20P” is 1 + 2/4 + 20/160 = 1.625 acres, about 6,576 m². See the rood and perch pages.
Chain. Gunter’s chain is 66 feet, and ten square chains make exactly one acre, which is why so many old plats are measured in chains and links.
Section and township. The US Public Land Survey System divides much of the country into townships of nominally 36 square miles, each split into 36 sections of nominally 640 acres. Because the system was laid out on a curved Earth and corrected along the way, real sections and townships can differ from these nominal sizes. A legal description such as “the NE 1/4 of Section 12” refers to a nominal 160 acres, but the surveyed figure on the plat is the one to rely on. See the section and township pages.
Old American surveys also used the US survey foot, which was retired for new work on 1 January 2023. It differs from the international foot by only 2 parts per million, which is far too small to matter for land area.
How to convert without mistakes
- Find the definition. For any variable unit, find out which local definition the document uses. The land record, the local revenue or land office, or a surveyor familiar with the area can tell you.
- Convert through a base unit. Go through square meters or square feet rather than chaining several traditional units together, and keep a few extra digits until the last step.
- Convert mixed units part by part. Areas such as “2 rai 1 ngan 50 square wah” or “1A 2R 20P” need each part converted and then added.
- Check against a known area. If the total implies an impossible plot size, or disagrees with the area in square meters printed on the same document, the definition is probably wrong.
Our units pages list the known regional variants of each unit, and the land area converter takes care of the arithmetic between units. To find the size of a plot in the first place, the Land Measure app measures it on a map or with GPS and reports the result in square meters, square feet, acres, hectares, and other international units, which you can then convert to the local unit. For legal or financial decisions, rely on the official record and, where needed, a licensed surveyor.