Circle Area Calculator for Land (Radius or Circumference)
A round pond, a circular garden or a plot with a curved boundary needs the area of a circle. Enter any one of radius, diameter or circumference and the calculator gives the area in the same unit squared, plus the land units used in Bangladesh and India.
Area = π × r² r is the radius. With the diameter d: area = π × d² ÷ 4. With the circumference C: area = C² ÷ (4π).
The same area in land units
How to measure a circular plot
- Find the centre. Stretch a tape across the widest part of the circle; the middle of that line is the centre and the whole line is the diameter.
- Measure from the centre to the edge for the radius, or simply use the diameter.
- If you cannot reach the centre (a pond, for example), walk the boundary with a measuring wheel or tape and use the circumference.
- Enter the figure above. The calculator converts the result to square feet, square metres, decimal, katha and bigha.
Worked examples
- A pond 100 feet across: radius 50 ft, area = 3.1416 × 50 × 50 = 7,854 sq ft = 18.03 decimal.
- A round garden with a 60 m boundary: area = 60² ÷ (4 × 3.1416) = 286.5 sq m = 3,084 sq ft.
- Radius 20 hat (30 ft): area = 3.1416 × 30² = 2,827 sq ft = 3.93 katha.
Frequently asked questions
What is the formula for the area of a circle?
Area = π × radius², where π is about 3.1416. If you know the diameter, halve it to get the radius. If you know the circumference, area = circumference² ÷ 12.566.
Is the area twice the circumference?
No. That is a common mistake. Circumference is a length (2πr) and area is a surface (πr²); they are not multiples of each other. A circle with a 10 ft circumference has an area of 7.96 sq ft, not 20.
How do I get the area in decimal or katha?
Convert the square feet: divide by 435.6 for decimal (satak) or by 720 for katha. The table under the calculator does this for you.
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