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Irregular Plot Area Calculator — 4 Sides + Diagonal

Four sides of different lengths? Enter all four and one diagonal across the plot. The area is split into two triangles and solved with Heron's formula — the only method that is accurate for real-world tede-mede plots.

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Convert this area in the main calculator → Bigha to Gaj table → Jamin napne ka calculator → Gaj to Sq.Ft converter →

The formula, step by step
  1. Measure the four sides: a (front), b (right), c (back), d (left).
  2. Measure one diagonal e that connects two opposite corners. It splits the plot into triangle 1 (a, b, e) and triangle 2 (c, d, e).
  3. For each triangle compute s = (x + y + z) / 2.
  4. Area of each triangle = √(s(s−x)(s−y)(s−z)).
  5. Total area = area of triangle 1 + area of triangle 2.
  6. Divide by 9 for Gaj, by 10.7639 for Sq. Meter, by 43,560 for Acre.

Worked example: sides 30 ft, 20 ft, 32 ft, 22 ft with a 36 ft diagonal. Triangle 1 has s = (30 + 20 + 36) / 2 = 43, area = √(43 × 13 × 23 × 7) ≈ 300.0 Sq.Ft. Running the same steps for triangle 2 gives roughly 352.3 Sq.Ft, so the plot is about 652 Sq.Ft ≈ 72.5 Gaj.

Without a diagonal? This page falls back to the average method — ((a + c) / 2) × ((b + d) / 2) — but the result is only an estimate and can be 10–20% off. Always measure the diagonal for a registry-ready number.

Irregular plot FAQ

How do you calculate the area of an irregular four-sided plot?
Measure the four sides (a, b, c, d) and one diagonal that splits the plot into two triangles. Compute each triangle's area with Heron's formula using the diagonal as the shared side, then add the two areas.

Tede mede plot ka area kaise nikale?
Charon side naap kar ek diagonal bhi naapein. Diagonal plot ko do tribhuj (triangles) me tod deta hai. Har tribhuj ka area Heron's formula (s = (a+b+c)/2) se nikaal kar dono ko jod dein. Without a diagonal the answer is only an average estimate and can be off by 10-20 percent.

What if my plot is a triangle?
Use three sides only. The main calculator has a dedicated Triangular mode that applies the same Heron's formula.

What if the diagonal is longer than the sides?
That is impossible geometry — a diagonal must be shorter than the two side-paths it shortcuts. The calculator reports 0 instead of a wrong area, so re-check your measurements.

Does this work in meters or gaj?
Yes. Everything is converted to feet first, so a plot measured in meters or gaj gives the same Sq.Ft result.