Land Plot Area Calculator (four sides)
Area of an irregular four-sided plot from its four sides and one diagonal, in square metres, hectares and acres.
Results
What this tool does
Real plots are rarely rectangles. Measure the four boundaries and then one diagonal across the middle, and the plot splits into two triangles whose areas Heron's formula gives exactly. If the measurements are impossible, such as a diagonal longer than two sides put together, no such plot exists and the result will not compute.
Formula
quadrilateral split by the diagonal into two triangles, Heron's formula on each
Variables
| Symbol | Meaning | Unit |
|---|---|---|
s1 | First side | m |
s2 | Second side | m |
s3 | Third side | m |
s4 | Fourth side | m |
dg | Diagonal | m |
A | Area | m² |
T1 | Area | m² |
T2 | Area | m² |
HA | Area | ha |
AC | Area | ac |
PE | Perimeter | m |
Worked example
- First side25 m
- Second side18 m
- Third side22 m
- Fourth side20 m
- Diagonal30 m
- Area444.63 m²
- Area224.67 m²
- Area219.96 m²
- Area0.04446 ha
- Area0.10987 ac
- Perimeter85.00 m
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.
Frequently asked questions
Why is the diagonal needed as well as the four sides?
Because four sides alone do not fix a shape. A quadrilateral with the same four sides can be squashed into many different shapes, each with a different area, unlike a triangle, which is rigid. Measuring one diagonal locks the shape and splits it into two triangles the calculation can handle.