Bigha, Katha, Satak and Decimal: a regional land-measurement manual
Understand why customary land units change by region and how to convert them through a consistent square-foot base.
The same unit name can represent different land areas
Customary land units developed locally, so a label such as Bigha or Katha can mean different square-foot areas across districts and countries. That makes a region selector essential. The AllFast West Bengal preset uses 1 Bigha = 20 Katha = 14,400 square feet. The Bangladesh preset used by this tool follows 1 Bigha = 20 Katha = 13,360 square feet and the site's configured 33-Decimal convention. These presets help with comparison, but a deed or survey can specify a different local basis.
Why square feet is a useful calculation base
A converter is more reliable when every input first becomes one neutral base unit. If U is a source unit, square feet = quantity × square-feet-per-U. Every destination value is then square feet ÷ square-feet-per-destination-unit. This avoids converting Bigha to Katha, rounding, then converting the rounded Katha to Decimal. Acre and hectare can also join the same calculation because one acre is 43,560 square feet and one hectare is approximately 107,639.104 square feet.
Worked West Bengal example
Take 2.5 Bigha under the West Bengal preset. Multiplying 2.5 by 14,400 gives 36,000 square feet. Because the preset defines 20 Katha per Bigha, the same area is 50 Katha. If Decimal is represented by 435.6 square feet, 36,000 ÷ 435.6 is about 82.64 Decimal. Keeping the unrounded square-foot area in the middle lets each destination value be calculated independently.
Worked Bangladesh example
Under the Bangladesh preset configured here, 1.5 Bigha equals 20,040 square feet and 30 Katha. With the preset's 33-Decimal-per-Bigha convention, the same area is 49.5 Decimal. Bangladesh also uses other customary terms in different places, so a buyer comparing an online listing with a khatian, mutation record or local survey should confirm which definition the source document uses.
Use cases in property discussion and planning
A regional converter is helpful when a seller quotes Bigha but a construction plan uses square feet, when an agricultural plot is compared with an acre-based listing, or when an inherited parcel needs a quick approximate metric equivalent. It can also help detect obvious transcription mistakes. If one document's converted area differs materially from another, that is a reason to investigate—not a reason to choose the more convenient number.
Where calculators must stop
Area conversion does not establish ownership, boundaries, encumbrances, mutation status or survey accuracy. Fractional customary units can create significant value differences in dense property markets. Before registration, partition, mortgage, development or purchase, use the standard recognized by the competent land authority and have boundaries checked by an appropriate survey professional. The calculator should support that process, not replace it.
Frequently asked questions
Is one Katha always one twentieth of a Bigha?
Not universally. It is true only within a regional standard that defines it that way.
Are Satak and Decimal interchangeable?
They are often treated as equivalent, but local records can define or use them differently. Follow the source document.
Why do online land converters disagree?
They may be using different regional definitions, especially for Bigha and Katha.