In Bihar, 1 Bigha = 20 Katha. That part never changes. What changes — and what confuses almost every land buyer — is how big that Bigha actually is on the ground, because Bihar quietly works with two different Katha sizes. This guide gives you the conversion table, the formula and worked examples for both standards, and shows you how to check which one applies to your land.
For the reverse direction, see our guide to converting Decimal to Katha in Bihar, and for instant Katha-to-Decimal calculations use our free Katha to Decimal converter.
Quick answer
- 1 Bigha = 20 Katha (everywhere in Bihar)
- At the common practical rate (1 Katha = 3.415 Decimal): 1 Bigha = 68.3 Decimal ≈ 29,751 sq ft ≈ 0.683 Acre
- At the Patna/Arrah revenue standard (1 Katha = 3.125 Decimal = 1,361.25 sq ft): 1 Bigha = 62.5 Decimal = 27,225 sq ft = 0.625 Acre
- 1 Bigha = 400 Dhur = 8,000 Dhurki
Bigha to Katha conversion table
The Katha count is the same at both standards — only the area it represents changes.
| Bigha | Katha | Decimal (3.415 rate) | Decimal (3.125 rate) |
|---|---|---|---|
| 0.5 | 10 | 34.15 | 31.25 |
| 1 | 20 | 68.3 | 62.5 |
| 2 | 40 | 136.6 | 125 |
| 3 | 60 | 204.9 | 187.5 |
| 5 | 100 | 341.5 | 312.5 |
| 10 | 200 | 683 | 625 |
| 20 | 400 | 1,366 | 1,250 |
The formula
Katha = Bigha × 20
Bigha = Katha ÷ 20
That is genuinely all there is to the unit conversion. Every complication in Bigha conversions comes afterwards, when Katha has to become square feet, Decimal or acres — and that step depends on which Katha size your district follows.
Worked examples
Example 1: Convert 7 Bigha to Katha and Decimal. 7 × 20 = 140 Katha. At the 3.415 rate that is 140 × 3.415 = 478.1 Decimal. At the 3.125 rate it is 140 × 3.125 = 437.5 Decimal. Same land on paper — a 40-Decimal difference purely from the standard used. This is exactly why two people can measure the same plot and disagree.
Example 2: Convert 45 Katha to Bigha. 45 ÷ 20 = 2.25 Bigha — in everyday language, 2 Bigha and 5 Katha.
Example 3: How many Bigha in 1 Acre? At the 3.125 standard, 1 Bigha = 62.5 Decimal, so 1 Acre = 100 ÷ 62.5 = 1.6 Bigha — the figure quoted in most of Bihar. At the 3.415 rate, 1 Acre ≈ 1.46 Bigha. When someone tells you “1.6 Bigha makes an acre,” they are using the 3.125 standard whether they know it or not.
Why the same Bigha has two sizes
A Bigha is always 20 Katha, but a Katha itself is defined differently in different records. The Patna/Arrah revenue tradition fixes 1 Katha at 1,361.25 square feet — exactly 3.125 Decimal. Much of the rest of Bihar, in everyday buying, selling and measurement practice, uses a larger Katha of 3.415 Decimal (about 1,487.6 square feet). Multiply either Katha by 20 and you get a Bigha — but the two Bighas differ by almost 2,526 square feet.
Neither side is “wrong.” They are two living standards, and your deed, your district’s practice and your local amin’s measurement decide which one governs your plot. What is wrong is mixing them inside one calculation — a mistake that quietly costs buyers lakhs on larger plots.
Bigha in other states (briefly)
Leave Bihar and the Katha count itself changes. In Assam, 1 Bigha = only 5 Katha, because the Assamese Katha is much larger (about 2,880 sq ft). In West Bengal a Bigha is again 20 Katha, but the Bengali Katha is just 720 sq ft, so a Bengal Bigha is 14,400 sq ft — nearly half of Bihar’s. Never carry a Bigha figure across a state border without converting it fresh.
Frequently asked questions
How many Katha are in 1 Bigha in Bihar? Exactly 20 Katha. Only the square-feet value of the Katha varies by standard and district.
How many square feet are in 1 Bigha in Bihar? 27,225 sq ft at the Patna/Arrah standard (20 × 1,361.25 sq ft). At the common 3.415 Decimal rate, about 29,751 sq ft.
How many Dhur are in 1 Bigha? 400 Dhur — 20 Katha × 20 Dhur. One Bigha also equals 8,000 Dhurki.
Is 1 Bigha the same all over India? No. A Bigha is a traditional unit with no single national size. Bihar uses 20 Katha per Bigha, Assam uses 5, and West Bengal’s 20 Katha add up to a far smaller area.
Which standard should I use for my land? Use the one in your land records and local revenue practice. For Patna and Arrah side documents, expect 3.125 Decimal per Katha; for much of the rest of Bihar, expect 3.415. When money is involved, confirm with the local revenue office before signing.
Bottom line
1 Bigha is always 20 Katha in Bihar — commit that to memory and you have half the system. For the other half, always ask “which Katha?” before trusting any square-feet or Decimal figure. Run your numbers through our Katha to Decimal converter, which uses the 3.415 rate, and read the Decimal to Katha guide if your documents are written in Decimal.
