Land Area Calculator

Land units in Bangladesh

Land in Bangladesh is bought, sold and recorded in a mix of units: decimal (also called shotangsho or shotok), katha, bigha and acre, alongside square feet for flats and small plots. The calculator defines every unit in square feet using these standard values:

Decimals in the table are rounded. Some handy figures:

• 1 katha = 80 square yards ≈ 66.89 square metres ≈ 1.6529 decimal
• 1 decimal ≈ 0.605 katha ≈ 40.47 square metres
• 1 acre = 100 decimal = 60.5 katha = 3.025 bigha
• 1 decimal = 100 ojutangsho

Is a bigha 33 decimal?

Almost, but not exactly. A standard bigha is 20 katha = 14,400 sq ft, and 14,400 ÷ 435.6 = 33.0579 decimal. People often say “1 bigha = 33 decimal” because it is easy to remember, but 33 decimal is 14,374.8 sq ft, which is 25.2 sq ft short of a full bigha. On 10 bigha that is 252 sq ft, about a third of a katha. The calculator always uses the exact figure.

Katha and bigha vary by region

The katha and bigha are traditional units, and their size has not always been the same from place to place. The calculator uses the standard Bangladesh values, 1 katha = 720 sq ft and 1 bigha = 20 katha = 14,400 sq ft, as its default.

If your deed (dalil), khatian or local surveyor uses a different katha, type its size in square feet in the Size of 1 katha box (anything from 1 to 10,000 sq ft). A bigha is then 20 of those katha. Square feet, decimal, acre and the metric units don’t change, because they have fixed definitions.

For example, with an illustrative katha of 1,000 sq ft, a 2,400 sq ft plot is 2.4 katha and 0.12 bigha, while it stays 5.5096 decimal.

How to measure a plot

• Measure along the ground, in a straight line, corner to corner. On a slope, keep the tape level. Feet, haat (1 haat = 18 inches = 1.5 ft), goj (1 goj = 3 ft) and metres are all accepted; the calculator converts them to feet first.
• Rectangle: if the corners are square, area = length × width. To check, measure both diagonals: in a true rectangle they are equal.
• Four sides (approximate): for a plot that is roughly rectangular but whose opposite sides differ a little, the usual shortcut is (north + south) ÷ 2 × (east + west) ÷ 2. It is exact only when opposite sides are parallel and the corners are square, so treat it as an estimate. The further the plot is from a rectangle, the bigger the error.
• Triangle: with all three sides, the area comes from Heron’s formula. The longest side must be shorter than the other two added together, or the sides can’t meet.
• Irregular plots: measure one or more diagonals to split the plot into triangles, work out each triangle and add the areas. This is more accurate than the four-sides shortcut.

Worked examples

Converting units

5 katha = 5 × 720 = 3,600 sq ft = 3,600 ÷ 435.6 = 8.2645 decimal, which is also 0.25 bigha.

10 decimal = 10 × 435.6 = 4,356 sq ft = 4,356 ÷ 720 = 6.05 katha.

Rectangle

A plot of 60 ft × 40 ft = 2,400 sq ft = 5.5096 decimal = 3.3333 katha.

Measured in haat, a plot of 40 × 30 haat is 60 × 45 ft = 2,700 sq ft = 3.75 katha = 6.1983 decimal.

Four sides

North 60 ft, south 64 ft, east 40 ft, west 44 ft: (60 + 64) ÷ 2 × (40 + 44) ÷ 2 = 62 × 42 = 2,604 sq ft = about 5.978 decimal = 3.6167 katha.

Triangle

Sides of 30, 40 and 50 ft give 600 sq ft = 1.3774 decimal = 0.8333 katha.

How to use the calculator

1. Choose Convert units to change an area from one unit to the others, or Area from measurements to work it out from the sides.
2. To convert, enter the area and pick its unit. For measurements, pick the shape and the unit the sides were measured in, then enter each side.
3. Leave the katha size at 720 sq ft unless your deed or surveyor uses a different katha.
4. Select Calculate area. You’ll see the area in decimal, katha and square feet, and a table with every other unit.

Use it for estimates

This calculator is for estimates and for checking figures. Before buying, selling or registering land, confirm the area with a government surveyor and the deed (dalil) and khatian. Field measurements, local practice and the legal record can differ from a quick calculation.