Land area units:
acres, hectares and square feet

The units that appear on land documents

Land is described in several systems at once. Science, government and international usage favour the hectare, a metric unit. Many property documents, farm listings and older records use acres. Urban plots are sold in square feet or square yards, and rural areas often have local units such as the guntha, cent and bigha.

Each is a perfectly good unit, but moving between them correctly is a place where money is lost. A farm priced per acre but measured in hectares, or a plot sold per square foot but surveyed in square metres, needs a clean conversion step, preferably written down.

The international acre, defined in 1959, is exactly 4,046.8564224 square metres. A hectare is exactly 10,000 square metres, a square 100 metres on a side. Those two definitions are the basis for all the rest.

It also helps to know how big the numbers feel. A football pitch is a bit under two acres, and a cricket ground is typically several acres. A hectare is roughly the size of a large football pitch including run-offs, which makes the metric figure easy to picture.

The conversion factors

A useful anchor is the hectare: 1 ha ≈ 2.471 acres ≈ 107,639 square feet. That means a hectare is a little under two and a half acres.

When you need a plot width and length from an area, remember that area alone does not fix the shape. An acre can be a square of about 208.7 ft per side or a long strip of 660 ft by 66 ft, the old chain-and-furlong shape that gave the acre its size. Check the dimensions on the survey sketch before you assume a frontage.

Worked example: a 2.5-acre plot

Go the other way. A 3-hectare farm is 3 × 2.4710538 = 7.413 acres, or 3 × 107,639 ≈ 322,917 square feet. A buyer pricing at ₹40 lakh per acre would pay about ₹2.97 crore for 7.413 acres, but only if the price quoted was indeed per acre and the 3 ha figure is from the title or survey.

A small plot gives a feel for the other end. 1,200 sq ft is 1,200 ÷ 43,560 = 0.0275 acre, or about 111.5 m². Each 100 square yards equals 900 sq ft.

Regional units and when to be careful

In south India, the cent (100 to an acre) and the guntha (40 to an acre) are common in registration documents. In Telangana and Andhra Pradesh you will often see guntha and acre together, with 40 guntha making an acre. Both are fixed by that ratio, so their sizes follow from the acre.

The bigha is different: its size varies by state and sometimes by district, with the same word meaning very different areas in different places. Never apply a single bigha-to-acre factor across state lines. Ask for the value from the local revenue records, or ask for the area in acres or square metres from the survey.

Also check whether a stated area is the gross area of a plot or the built-up or saleable portion. Per-square-foot prices for apartments often use carpet or super built-up areas, which are not interchangeable with the land area on a title document.

Converting a price rate from one unit to another

Land is often quoted per unit of area, so the rate has to be converted along with the area. If a plot is advertised at ₹500 per square foot, the same rate per acre is 500 × 43,560 = ₹2,17,80,000, or about ₹2.18 crore. A rate per square foot and a rate per acre are the same price in different units.

The conversion works in the opposite direction by division. A rate of ₹5,00,000 per guntha is ₹5,00,000 ÷ 1,089 = ₹459 per square foot, and ₹5,00,000 × 40 = ₹2 crore per acre. The factors are the same as for the areas, applied in reverse.

Check this whenever two sellers quote different units. A cheaper-looking rate per cent may be dearer per square foot than a rate per guntha because a cent is only 435.6 sq ft while a guntha is 1,089. Convert both to a common unit before comparing.

Mistakes that distort land areas

• Converting an area by the length factor. 1 m = 3.28084 ft, but 1 m² = 10.7639 ft². Area factors are the square of the length factors.
• Mixing up acre and hectare when reading foreign listings. An asking price of 1,000,000 per hectare is 404,686 per acre.
• Using 40 guntha for a bigha or 100 cents for a guntha. Check each unit's ratio to the acre before you compute.
• Rounding too early. 43,560 × 2.5 is 108,900, but 43,600 × 2.5 is 109,000, a 100 sq ft error.
• Taking an informal figure from a seller as the area on record. The registered area is the one that counts.

For purchases and legal documents, confirm the area against the title deed or a licensed survey. A conversion shows what the numbers imply, but only the land records state what the plot actually is.