Chatak to Square Feet: 45 ft², a Sixteenth of the Kolkata Katha
Chatak (chhatak) to square feet, m² and gaj: 45 ft², 16 to a 720 ft² Bengal katha, 320 to the bigha. Reads and writes "3 katha 5 chatak"; refuses the weight.
Chatak to Square Feet — 45 ft², a sixteenth of the Kolkata katha
A chatak (chhatak) is the rung under the Bengal katha: sixteen to a 720 ft² katha, so one chatak is 45 ft², exactly 5 gaj, 4.181 m². This page converts it, reads and writes the “3 katha 5 chatak” form the Kolkata and Dhaka listings use, and says where the same word is a weight or belongs to a ladder that has no chatak in it.
The chatak is the smallest unit a Kolkata plot is quoted in, and a listing that says "3 katha 5 chatak" is using two rungs of one ladder. The ladder is the Bengal measure: 20 katha to a 14,400 ft² bigha, 16 chatak to the katha. That fixes the katha at 720 ft² and the chatak at 45 ft², which is exactly five square yards, or gaj, and 4.18063680 m² on the international foot. Sixteen chatak make a katha, 320 make a bigha, and an acre is 3 bigha 8 chatak with nothing left over. The same 720 ft² katha is what Bangladesh's Ministry of Land publishes, so the Dhaka chatak is the same 45.
Two things go wrong with the word. The first is that it travels: in the Assam Valley the rung under the katha is the lessa, in Bihar and the Nepal Terai it is the dhur, and a chatak worked out from those kathas is a unit nobody keeps a record in. The second is that outside land, a chatak is a weight, a sixteenth of the old seer, about 58 grams, and a rice or ghee chatak has no square feet at all. This page converts the Bengal chatak, writes your area back in the katha-and-chatak form both ways, and refuses the rest. The katha itself, with its four regional sizes, is on this site's katha page; the bigha schedule is on the bigha page.
| Chatak | — |
|---|---|
| Written as the record writes it | — |
| Square feet | — |
| Square metres | — |
| Gaj (square yards) | — |
| Acres · decimal | — |
| Bigha on this ladder | — |
| One chatak here | — |
| 5 · 8 · 10 · 16 chatak | — |
| How good is this figure | — |
| What the wrong chatak would give | — |
The chatak is a sixteenth of a katha, and the katha it divides is the Bengal one. No document fixes the chatak on its own; the 1900 survey manual that sets out the Bengal measure gives it as a share, 16 to the katha, under a katha of 720 ft² and a bigha of 20 katha. So the 45 ft² is arithmetic on that ladder, and it holds exactly wherever the 720 katha holds: Kolkata, Howrah, the south Bengal districts, and Bangladesh, whose Ministry of Land prints the same 720. The check that the ladder closes is the acre: 43,560 divided by 45 is 968 chatak, which is 3 bigha and 8 chatak, the figure the manual itself gives for an acre. A converter that starts from a different katha and divides by 16 has invented a chatak, because the other kathas are not divided into sixteen.
“3 katha 5 chatak” is one number written on two rungs, and both rungs have to be converted. The form is the same as feet and inches. 3 katha 5 chatak is 48 plus 5, 53 chatak, 2,385 ft². Readers convert the katha and drop the chatak, which throws away 225 ft² on that plot, or read the 5 as a decimal fraction of a katha and get 3.5 katha, which is 2,520 ft² and 135 too many. The chatak count runs to 15; a 16 carries into the next katha, and a listing that says 3 katha 16 chatak has miscounted. Going the other way, 2,000 ft² is 44.44 chatak, which the record writes as 2 katha 12.44 chatak, and the fraction is normal: a survey figure in decimals converted to the katha ladder rarely lands on a whole chatak.
The Bengal record is in decimals, and the chatak is 0.1033 of one. The West Bengal Land Reforms Act, 1955 uses the words bigha, katha, cottah and chatak nowhere; it works in decimals, one hundredth of an acre, 435.6 ft². So the porcha or the record of rights will carry 5.475 decimal where the broker says 3 katha 5 chatak, and the two are the same land only if the katha is 720. A chatak is 45/435.6 decimal, which is 0.10331, and a decimal is 9.68 chatak. Bangladesh keeps the same acre-and-decimal record, and its ministry table rounds the bigha to 33 decimal, which is 14,374.8 ft²: 25.2 ft² short of 320 chatak, a little over half a chatak. This page prints 33.058, because that is what twenty katha of sixteen chatak come to.
Outside Bengal the word is a weight, or the ladder has no such rung. In the Assam Valley the katha is 2,880 ft² and divides into 20 lessa of 144 ft²; there is no chatak in that ladder, and 2,880 divided by 16 gives a 180 ft² unit that no Assam document names. In Bihar and the Nepal Terai the rung under the katha is the dhur, twenty to the katha, so a “Patna chatak” of 85 ft² is arithmetic on a ladder that does not have one. And in kitchens and bazaars across north India and Bangladesh a chatak, chhatak or chittack is a sixteenth of a seer, about 58 grams on the old seer of roughly 933 grams: the unit a rice or ghee quantity is given in. That chatak has no square feet, and this page declines to convert it rather than print a number that would look like an area.
Numbers you will meet that are wrong. 1 chatak = 50 ft² is a rounding of 45 that overstates every chatak by 11%; on 3 katha 5 chatak it adds 265 ft², most of a katha of the error hidden in a small-looking figure. 1 chatak = 180 ft² is the Guwahati katha divided by sixteen, a rung the Assam manual does not have, and it is four times the Bengal chatak. 1 chatak = 4.18 m² is a fair rounding, but 4.2 m² on a 100-chatak plot adds almost 2 m²; the exact figure is 4.1806368. 1 katha = 20 chatak is the dhur count moved onto the wrong word: it makes a chatak 36 ft² and a 5-chatak share 45 ft² short. 1 chatak = 58 g is right, and it is the other chatak.
Exact by definition: 1 ft = 0.3048 m, so 1 ft² = 0.09290304 m²
(NIST Handbook 44, Appendix C; the international foot has been the only U.S. foot since 1 January 2023,
85 FR 62698); 1 gaj = 1 yd² = 9 ft²; 1 acre = 43,560 ft²; 1 decimal = 1/100 acre =
435.6 ft². Every metric, gaj, acre and decimal figure here follows from those and from the
45 ft² chatak, with no rounding until the screen runs out of digits.
The 45 ft² chatak, West Bengal and the Assam Barak Valley: Manual of Mensuration and
Surveying for Mandals and Patwaris in Assam, Shillong 1900, section 30(b) “Bengal measure”:
16 chatak = 1 katha of 720 sq ft, 20 katha = 1 bigha = 1,600 sq yd, “used in the Surma Valley
districts”, with the cross-check 1 acre = 3 bigha 8 chatak, which closes exactly. Read from an
Internet Archive snapshot of the Assam Revenue and Disaster Management Department's own URL, because
the host did not respond. The same document and citation this site's katha and bigha pages rest on. A
government publication and not a statute: the West Bengal Land Reforms Act, 1955 defines no such unit,
and which ladder the Barak Valley districts use in their records today could not be confirmed from a
modern Assam source, so that row carries the date. The 45 itself is 720 / 16, arithmetic on the
manual's figures rather than a line the manual prints.
Bangladesh: Ministry of Land, Government of Bangladesh, “Standard Units of Land Measurement
in Bangladesh”: 1 Katha = 720 Sq Feet, 20 Katha = 1 Bigha, 1 Acre = 60.5 Kattah. The chatak is
carried here as a sixteenth of that katha on the Bengal ladder; a ministry table, not a statute, and
Bangladesh is metric by law.
The refusals use the same manual's section 30(a) for the Assam measure (144 sq ft = 1 lessa,
20 lessa = 1 katha, 5 katha = 1 bigha: no chatak), the Bihar Revenue Glossary and the Nepal building
by-laws reference book cited on the katha page for the dhur ladders, and, for the weight, the
traditional seer of about 933 grams divided into 16 chatak, stated here as convention with no
statute cited. No gram figure is offered as a conversion.
Worked example
A Kolkata listing says the plot is 3 katha 5 chatak. How many square feet is that, and what will the record show?
- On the Bengal measure a katha is 720 ft² and holds 16 chatak, so a chatak is 45 ft², exactly 5 gaj. 3 katha 5 chatak is 3 × 16 + 5 = 53 chatak.
- 53 × 45 = 2,385 ft². In metres 2,385 × 0.09290304 = 221.5738 m²; in gaj 2,385 ÷ 9 = 265.
- The West Bengal record is in decimals: 2,385 ÷ 435.6 = 5.475 decimal, or 0.0548 acre. On the bigha ladder it is 53 ÷ 320 = 0.165625 bigha.
- Dropping the 5 chatak would give 2,160 ft², 225 short; reading 3 katha 5 as 3.5 katha would give 2,520, 135 over. At the 50 ft² rounding the plot would be 2,650, 265 too many.
2,385 ft², 221.57 m², 265 gaj, 5.475 decimal. The 45 is 720 ÷ 16 on the 1900 survey manual's Bengal measure, the same 720 the Bangladesh Ministry of Land prints; no West Bengal statute repeats it, and the porcha will carry decimals.
14 values on this page were driven in a browser and compared with independently derived figures on 2026-09-09 (2414 values across 203 calculators site-wide).
Questions
How many square feet is one chatak?
45 ft² in West Bengal and Bangladesh: sixteen chatak make a 720 ft² katha, and 720 ÷ 16 = 45. That is exactly 5 gaj (square yards), 4.1806 m² and 0.1033 decimal. The figure holds wherever the 720 ft² Bengal katha holds; it is arithmetic on the 1900 survey manual's Bengal measure and on the Bangladesh Ministry of Land katha, not a line either prints on its own, and no statute in either place defines the unit.
How do I convert 3 katha 5 chatak to square feet?
Convert both rungs and add them, the way feet and inches work. 3 katha is 3 × 720 = 2,160 ft²; 5 chatak is 5 × 45 = 225 ft²; together 2,385 ft², 221.57 m². Do not read the 5 as a decimal fraction (3.5 katha is 2,520 ft²) and do not drop it (2,160 ft² is 225 short). The chatak count runs from 0 to 15; a listing that says 16 chatak or more has miscounted a katha.
Is a chatak the same everywhere, and what about the chatak of rice?
No. As land it exists only on the Bengal ladder: Kolkata, south Bengal, Bangladesh and, on a 1900 manual, the Barak Valley. Assam's Brahmaputra Valley divides its 2,880 ft² katha into 20 lessa, and Bihar and the Nepal Terai divide theirs into 20 dhur, so a chatak worked out from those kathas is a unit nobody keeps a record in. The chatak of rice or ghee is a weight, a sixteenth of the old seer, about 58 grams, and has no square feet at all; this page refuses to convert it.