Katha to Square Feet Converter

A katha is a local unit, so the number depends on the district

Katha is a land unit from the Bengal and Bihar systems of measurement, and it never had a single national value. Each state set its own ratio when the old revenue surveys were codified, and those ratios still govern land records today. The same word covers 720 sq ft in Kolkata, 1,361.25 sq ft in Bihar, 2,880 sq ft in Assam and 3,645 sq ft in the Nepal Terai.

That spread is not a rounding error. A plot recorded as 10 katha is 7,200 sq ft in Kolkata and 36,450 sq ft in Nepal, a factor of five. Anyone converting a land record without a region attached is guessing.

West Bengal and Assam share a bigha of 14,400 sq ft but not a katha. West Bengal divides that bigha into 20 parts and Assam divides it into 5, which is why Assam's katha is four times larger. Read a land deed that lists bigha and katha together and the ratio tells you which system the clerk used.

Bihar: 1 katha = 1,361.25 sq ft

Bihar's revenue system divides a bigha of 27,225 sq ft into 20 katha, and each katha into 20 dhur. That gives a katha of 1,361.25 sq ft and a dhur of 68.0625 sq ft, the figure that appears on most Bihar land receipts.

The 27,225 sq ft bigha is a neat unit in the old survey chain: it is 5/8 of an acre. Bihar's Revenue and Land Reforms Department publishes the conversion in its land records guidance, and the district registries use it when a sale deed states area in katha and dhur.

Sixteen katha is half an acre exactly, which makes mental arithmetic easier than it looks. A plot of 3 katha 10 dhur is 3.5 katha, so 3.5 x 1,361.25 = 4,764.38 sq ft.

The same 1,361.25 sq ft katha shows up in the eastern districts of Uttar Pradesh, where the bigha is also 27,225 sq ft. Western UP uses a different bigha of 27,000 sq ft and a katha near 1,350 sq ft, so the district matters as much as the state.

West Bengal and Bangladesh: 1 katha = 720 sq ft

Kolkata's katha, often spelled cottah on older deeds, is 720 sq ft. Twenty katha make a bigha of 14,400 sq ft, and each katha splits into 16 chhatak of 45 sq ft. This is the unit behind most residential plot listings in Kolkata, Howrah and the surrounding districts, and the same standard carried into Bangladesh.

The West Bengal Land and Land Reforms Department records plot area in katha and chhatak in the record of rights, so a buyer comparing a 4 katha listing with a 3,000 sq ft listing is comparing 2,880 sq ft with 3,000 sq ft, not the other way around.

Because a Kolkata katha is close to 67 sq m, a 3 katha flat plot is about 200 sq m, which is the size most developers quote in square metres. A 5 katha plot is 3,600 sq ft, roughly the footprint of a mid-size apartment building with parking.

Bangladesh uses the same 720 sq ft katha and the same 20 katha bigha, but adds the decimal, where 1 decimal is 435.6 sq ft. A 10 decimal plot is 4,356 sq ft, or 6.05 katha. Mixing decimal and katha in one conversation is a common source of confusion in Dhaka land offices.

Assam and Nepal: the two larger kathas

Assam built its revenue units on the bigha of 14,400 sq ft, the same area as West Bengal's, but divided it into 5 katha instead of 20. That makes the Assamese katha 2,880 sq ft, four times the Kolkata figure. Each katha holds 20 lessa of 144 sq ft.

Nepal's Terai districts use the kattha of 3,645 sq ft, with 20 kattha to a bigha of 72,900 sq ft and 20 dhur to a kattha. That bigha is 1.6736 acres, notably larger than the Indian bigha. The Nepal Department of Land Management and Archive publishes the standard in its land measurement guidance.

Notice that Assam's bigha matches West Bengal's while its katha does not. A deed that gives area in bigha alone is ambiguous across the two states only in the katha breakdown, not in the total area.

Nepal complicates things further because the hill districts use ropani, not kattha. One ropani is 5,476 sq ft and 16 ropani make a ropani block of 87,616 sq ft, so a hill plot and a Terai plot need separate conversions before any price comparison. Convert ropani to square feet first, then apply the Terai kattha of 3,645 sq ft if you need both figures in one table.

Worked example: 5 katha in Bihar

Take a plot in Patna district recorded as 5 katha. The calculator loads this case by default.

• Square feet. 5 x 1,361.25 = 6,806.25 sq ft.
• Square metres. 6,806.25 / 10.7639104 = 632.32 sq m.
• Bigha. 5 / 20 = 0.25 bigha.
• Acres. 6,806.25 / 43,560 = 0.15625 acre.
• Dhur. 5 x 20 = 100 dhur.

Now run the same 5 katha through the West Bengal standard. The calculator returns 3,600 sq ft, which is 334.45 sq m and 0.08264 acre. Both answers are correct for their region, and they differ by 3,206.25 sq ft, nearly half the Bihar total.

Reverse the direction as a check. Enter 6,806.25 sq ft with Bihar selected and the calculator returns 5.0000 katha. Enter 3,600 sq ft with West Bengal selected and it returns 5.0000 katha. The round trip holds because the division uses the same ratio as the multiplication.

A land agent quoting 5 katha in a city where the recorded standard is 720 sq ft would be selling 3,600 sq ft, not 6,806 sq ft. Ask for the sq ft figure on the deed before comparing prices per katha across states.

Converting square feet back to katha

The reverse direction matters more than it seems, because bank valuations, municipal tax records and online listings often state area in square feet while the deed states katha. Divide the square footage by the regional katha size and the answer falls out.

One acre is 32 katha in Bihar, which is a handy benchmark: 32 x 1,361.25 = 43,560. The same acre is 60.5 katha in Kolkata and 15.125 katha in Assam, so an acreage figure in a broker's message tells you nothing about the katha count until the region is fixed.

Round with care. A 5,000 sq ft plot in Bihar is 3.6731 katha, which a clerk may record as 3 katha 13.5 dhur. Lose the fraction and a buyer can underpay or overpay by several hundred square feet.

Which unit appears on the deed

Indian and Nepali land records do not use one vocabulary. The table below maps what a buyer is likely to see on a sale deed against the unit that officials use for registration and tax.

Two checks settle most disputes. First, ask for the area in square feet as well as katha, and confirm the two figures agree at the regional ratio. Second, compare the deed area with the plot dimensions on the survey map: a 5 katha Bihar plot of 6,806.25 sq ft might measure 60 ft by 113.4 ft, and a site visit can confirm those bounds.

The state revenue portals publish the ratios, but the district office is the authority for a specific plot. When the numbers on a deed and a tax record disagree, the district land records office resolves it, not an online converter.

Common conversion mistakes

Most errors in katha arithmetic come from four habits. Each one is easy to avoid once named.

The sub-unit trap deserves a closer look. A Bihar deed reading 3 katha 15 dhur means 3 + 15/20 katha, which is 3.75 katha, or 5,104.69 sq ft. Type 3 into the calculator and you get 4,083.75 sq ft, a shortfall of 1,020.94 sq ft, about the size of a small flat.

The acre trap shows up in valuation. A valuer who prices land at 8 lakh per bigha and then applies it to 20 katha of a Kolkata plot prices 14,400 sq ft, while the plot holds 20 katha of 720 sq ft, which is 14,400 sq ft. The numbers agree there by coincidence; in Bihar the same 20 katha is 27,225 sq ft, and the per bigha rate would underprice it by 47%.