Land Area Calculator
Find the area of a plot from its sides, including uneven four-sided plots, triangles and trapezoids.
About the Land Area Calculator
Uneven four-sided plots can't be measured from the sides alone: measure one diagonal too, which splits the plot into two triangles, and use Heron's formula for each. Heron: area = √(s(s − a)(s − b)(s − c)), where s is half the perimeter. For many-sided plots, split into triangles or use GPS points (map area calculator).
The formula
Heron: A = √(s (s − a)(s − b)(s − c)), s = (a + b + c) ÷ 2
Worked example
Example: Plot area = 2,879 ft² · 267.5 m²
- Inputs: Lengths in: Feet; Plot shape: Four sides + one diagonal; Side A: 66; Side B: 44; Side C: 68; Side D: 42; Diagonal (D–A corner to B–C corner): 79.
- Formula: Heron: A = √(s (s − a)(s − b)(s − c)), s = (a + b + c) ÷ 2
- Result: Plot area = 2,879 ft² · 267.5 m²
Questions people ask
Why do I need a diagonal?
Four sides alone can make many different shapes with different areas.
Is this a legal survey?
No; official boundaries come from a licensed surveyor and land records.