Land Area Calculator
Calculate plot area from its shape and dimensions, in every Indian unit at once.
Plots in India are rarely neat rectangles, and they are quoted in whichever unit the seller prefers. This calculator handles rectangular, triangular, trapezoidal and irregular four-sided plots, and converts the result into every unit at once — square feet, gaj, acre, hectare, guntha, cent, kanal and ground.
Plot shape and dimensions
Result
Fill in the fields above and your result will appear here.
What the Land Area Calculator does
The important detail with an irregular plot is that four side lengths do not determine an area. The same four sides can enclose different areas depending on the angles, which is why a surveyor measures a diagonal. Splitting the plot into two triangles along that diagonal gives an exact answer.
For triangular plots the tool uses Heron's formula, which needs only the three side lengths and no angles — practical when you are measuring with a tape on site.
How to use this tool
- Choose the shape that matches your plot. Use "irregular four-sided" for anything that is not a true rectangle.
- Select the unit your measurements are in — feet, metres or yards.
- Enter the side lengths. For an irregular plot you must also measure the diagonal between opposite corners.
- For a trapezium, enter the two parallel sides and the perpendicular distance between them, not the slanting side.
- Add a rate per square foot to value the plot, then read the conversion table for the unit your documents use.
Formula and method
Rectangle: Area = Length × Width
Triangle (Heron): s = (a + b + c) ÷ 2
Area = √(s(s−a)(s−b)(s−c))
Irregular quadrilateral:
Split along the diagonal, then
Area = Heron(a, b, diagonal) + Heron(c, d, diagonal)
Trapezium: Area = (a + c) ÷ 2 × perpendicular height
Circle: Area = π × radius²
Conversions: 1 acre = 43,560 sq ft · 1 gaj = 9 sq ft
1 guntha = 1,089 sq ft · 1 cent = 435.6 sq ft
Worked example
Example: a 60 × 40 foot plot
| Area | 2,400 sq ft |
| Square yards (gaj) | 266.67 |
| Acres | 0.0551 |
| Guntha | 2.20 |
| At ₹4,500 per sq ft | ₹1,08,00,000 |
2,400 square feet is also exactly one ground, the unit used for urban plots in Chennai — which is why the conversion table matters when documents and listings use different units.
What your result means
Square feet is the working unit for construction and for most urban transactions.
Gaj — the square yard — is how plots are quoted across much of north India. One gaj is nine square feet.
Acre and hectare matter for agricultural land and for anything recorded in revenue documents.
If the area you calculate differs from the sale deed by more than a percent or two, do not proceed on the calculation. Get a licensed surveyor to measure it.
Important considerations
- Measure the diagonal for any plot that is not a true rectangle. Assuming right angles on a slightly skewed plot can overstate the area by several percent.
- Built-up area, carpet area and super built-up area are different things and none of them is the plot area. RERA requires carpet area to be disclosed for apartments.
- Boundary walls sit on the boundary, so the usable internal area is slightly less than the plot area.
- Revenue records may state area in local units that vary by state. Use the state land unit converter to check.
- Setback rules under local building bylaws limit how much of a plot can actually be built on. The plot area is not the buildable area.
Limitations of this tool
- It assumes a flat plot. Sloping ground has a larger surface area than its plan area, which affects construction but not the recorded area.
- Plots with more than four sides, or with curved boundaries, need to be split into simpler shapes and calculated separately.
- It cannot substitute for a licensed survey. For a transaction, the registered document and a surveyor's measurement govern.
Frequently asked questions
How do I calculate the area of an irregular plot?
Measure all four sides and one diagonal, then choose the irregular four-sided option. Four sides alone are not enough — the same four lengths can enclose different areas depending on the angles.
How many square feet is one gaj?
One gaj is one square yard, which is exactly nine square feet. A 100 gaj plot is 900 square feet.
How many square feet in an acre?
43,560 square feet. An acre is also 4,840 square yards, or about 4,047 square metres.
Should I trust this over the sale deed?
No. The registered sale deed and the state land records are what govern a transaction. Use this to check whether what you are being shown matches what is recorded, and engage a licensed surveyor if they differ.