About this converter
Katha (also spelled kattah, kotha, or written কাঠা in Bangla) is one of the most widely used traditional land units in eastern South Asia. In West Bengal, Bangladesh, Assam, and Tripura the standard katha is 720 square feet. In Bihar and parts of Jharkhand the customary katha is much larger at 1361.25 square feet — almost twice the Bengal figure. This converter handles both standards and additionally maps katha to bigha, decimal (shotok), acre, and hectare.
Conversion formula
For the Bengal / Bangladesh standard, square feet = katha × 720. For the Bihar standard, square feet = katha × 1361.25. To go in reverse, divide the square-feet value by 720 (Bengal) or 1361.25 (Bihar).
Worked example
You are buying a plot listed as 5 katha in Kolkata. That is 5 × 720 = 3,600 sq ft, or about 8.27 decimal (since 1 decimal = 435.6 sq ft), or 0.083 acre, or 0.25 bigha. The converter above gives every one of these equivalents instantly.
How katha relates to bigha and acre
In the Bengal standard, 20 katha = 1 bigha = 14,400 sq ft, and 3.025 bigha = 1 acre. So 5 katha is one-quarter of a Bengal bigha, and roughly one-twelfth of an acre. The Bihar bigha is 20 × 1361.25 = 27,225 sq ft, which is closer to two-thirds of an acre.