Plot area calculator for rectangular, irregular and triangular land

How do I calculate the area of a 4-sided plot with different sides?

Measure all four sides and one diagonal, then treat the plot as two triangles. Each triangle’s area comes from its three sides with Heron’s formula: s = (a + b + c) ÷ 2, area = √(s × (s − a) × (s − b) × (s − c)). Add the two triangle areas together.

Example: sides of 50, 40, 45 and 42 ft with a 60 ft diagonal. Triangle one (50, 40, 60) is about 992 sq ft, triangle two (45, 42, 60) about 944 sq ft, so the plot is about 1,936 sq ft — roughly 215 gaj or 7.1 marla.

The diagonal matters because four sides alone don’t fix a shape: the same four lengths can make a squarer plot or a squashed one. Without it, the calculator shows the largest area those sides could possibly enclose, which is close to the real figure only when the corners are near 90°.

Is the “average of opposite sides” method accurate?

Only for a true rectangle. The common shortcut — (average of two opposite sides) × (average of the other two) — always gives a figure equal to or larger than the real area, never smaller.

For plots with near-square corners the gap is small, often under 1%. For a plot with a slanted side or one sharp corner it can be several percent, which matters when land is priced per square foot or per gaj. The calculator shows both figures side by side so you can see the difference for your own plot.

How do I find land area in square feet from feet measurements?

Multiply the measurements in feet to get square feet: length × width for a rectangle, or the two-triangle method for an irregular plot. Then divide to convert: 9 sq ft = 1 gaj (square yard), 272.25 sq ft = 1 marla, 1,089 sq ft = 1 guntha, 435.6 sq ft = 1 cent and 43,560 sq ft = 1 acre.

If you measured in metres, 1 sq m = about 10.76 sq ft. If the measurement is in karam, as on many Punjab and Haryana revenue maps, 1 karam = 5.5 ft, so 1 sq karam = 30.25 sq ft and 9 sq karam make 1 marla.

How do I calculate the area of a triangular plot from three sides?

Use Heron’s formula — you don’t need the height. Add the three sides and halve it to get s, then area = √(s × (s − a) × (s − b) × (s − c)). A plot with sides of 60, 45 and 50 ft is about 1,101 sq ft.

Any two sides must add up to more than the third. If they don’t, the sides can’t meet, and the calculator tells you which side to re-check — usually a swapped digit or a side measured in a different unit.

What if my measured area doesn’t match the land record?

Small differences are normal — tape sag, measuring to the inside of a wall, or rounding in old records can account for a few percent. A bigger gap is worth checking: it can mean a boundary has shifted, a road was widened, or the plot was never quite where the family thought.

The legal area is the one in your record of rights and survey map. If the numbers don’t agree, apply for an official demarcation at the tehsil or survey office. If you can’t get to the plot, you can outline it on a satellite map to cross-check from abroad.