Most real plots aren't perfect rectangles. Calculate area for triangular, circular, trapezoidal, and irregular four-sided land parcels — then see the result in every standard Indian land unit at once.
Key Takeaways
- Most real land parcels in India aren't perfect rectangles — roads curve, canals cut across boundaries, and adjoining plots rarely line up neatly, which is why triangle, trapezoid, and irregular-quadrilateral formulas come up constantly in practice.
- Any triangle's area can be found from just its three side lengths using Heron's formula, without needing to know any angle or height directly — useful since angles are much harder to measure accurately on-site than straight-line distances.
- A four-sided plot can be measured with five tape measurements, not four: the four boundary sides plus one diagonal, which splits it into two triangles you can solve independently and add together.
What This Land Area Calculator Does
This calculator works out the area of a plot of land in whatever shape it actually is, not just the simple rectangle most basic calculators assume. It covers five common shapes: a straightforward Rectangle or Square, a Triangle from its three side lengths using Heron's formula, a Circle from its radius or diameter, a Trapezoid from two parallel sides and the height between them, and an Irregular Four-Sided Plot from its four boundary measurements plus one diagonal, split into two triangles. Every result is shown in square feet and converted instantly to square metres, square yards, acres, cents, gunthas, and hectares, so you can compare it against a sale deed or a builder's quote in whatever unit it's written in.
Everything runs entirely in your browser. No measurement you enter is sent to a server, logged, or stored anywhere — close the tab and it's gone. There's no signup, no email wall, and no ads inside the calculator itself. For a state-specific Bigha or Katha conversion, or a Carpet-to-Super-Built-up calculation for an apartment, this links through to the dedicated Square Footage Calculator rather than duplicating those features here.
How to Use This Land Area Calculator
1. Rectangle / Square
- Enter Length and Breadth.
2. Triangle
- Measure all three sides of the triangular plot.
- Enter them — no angle needed.
3. Circle
- Choose whether you know the Radius or Diameter.
- Enter that measurement.
4. Trapezoid
- Enter both Parallel Sides.
- Enter the perpendicular Height between them.
5. Irregular 4-Sided Plot
- Walk the boundary and measure all four sides in order (AB, BC, CD, DA).
- Measure the diagonal from the first to the third corner (A to C).
- Enter all five measurements.
The Land Area Formulas, Explained
- Rectangle: Area = Length × Breadth
- Triangle (Heron's Formula): s = (a+b+c)/2; Area = √[s(s−a)(s−b)(s−c)]
- Circle: Area = π × r²
- Trapezoid: Area = ½ × (a+b) × h
- Irregular Quadrilateral: split into two triangles along one diagonal, find each with Heron's formula, and add them
Worked example (Irregular 4-Sided Plot): AB = 50 ft, BC = 45 ft, CD = 55 ft, DA = 48 ft, diagonal AC = 65 ft.
- Triangle ABC (sides 50, 45, 65): s = 80; Area ≈ 1,122.5 sq ft
- Triangle ACD (sides 65, 55, 48): s = 84; Area ≈ 1,290.8 sq ft
- Total Area = 1,122.5 + 1,290.8 ≈ 2,413.3 sq ft
The same diagonal-split logic is exactly how a surveyor or a revenue department sketch handles an odd-shaped plot on paper — break it into triangles, solve each with Heron's formula, and sum the results.
Worked Example Reference Table
The five worked examples above, side by side, showing how differently the same rough "plot size" reads depending on shape.
| Shape | Inputs | Area (sq ft) |
|---|---|---|
| Rectangle | 60 × 40 ft | 2,400 |
| Triangle | Sides 50, 60, 70 ft | 1,469.7 |
| Circle | Radius 25 ft | 1,963.5 |
| Trapezoid | Sides 80 & 50 ft, height 40 ft | 2,600 |
| Irregular 4-Sided | 50/45/55/48 ft, diagonal 65 ft | 2,413.3 |
Quick Definitions
Heron's formula calculates a triangle's area using only its three side lengths, without needing any angle or height measured directly — it works by first finding the semi-perimeter (half the total of all three sides) and using that in a square-root expression. An irregular quadrilateral is any four-sided shape where the sides and angles aren't all equal, which describes most real land plots more accurately than a rectangle does.
Frequently Asked Questions
Not directly. For a five-or-more-sided plot, the same diagonal-split idea still applies: divide the shape into triangles from one corner, measure each triangle's sides, and sum the areas using Heron's formula for each — this calculator's Triangle mode can be used repeatedly for that.
It's exact, provided your five measurements (four sides and the diagonal) are accurate and the shape is a simple, non-self-intersecting quadrilateral. Measurement error in the field is usually the bigger source of inaccuracy than the method itself.
Licensed surveyors typically use a total station or GPS/GNSS equipment to record precise boundary coordinates, then calculate area using coordinate geometry (the shoelace formula) rather than manual tape measurements. This calculator is for quick estimates, not a substitute for a professional survey in a real transaction.
Guntha is shown directly in the results list. For Bigha and Katha, which vary significantly by state, use the state-wise Bigha converter on the Square Footage Calculator instead of assuming a single national conversion.
A rectangle's right angles mean length times breadth fully determines its area. An irregular quadrilateral's angles are unknown, so the diagonal is what pins the shape down into two solvable triangles — without it, four side lengths alone don't uniquely determine the area.
No. Every calculation runs locally in your browser using JavaScript; nothing you enter is transmitted to any server, logged, or saved once you close or refresh the page.