About this calculator
Irregular plots are often measured this way.
How to use it
- Enter the parallel sides.
- Enter the height.
- Optionally enter the slanted sides.
The formula
Area = ½ × (a + b) × h
- a, b
- parallel sides
- h
- distance between them
Worked example
Parallel sides 10 and 6, height 4
- Area = ½ × 16 × 4 = 32.
- Median = 8.
What the result means
For land, measure the height at right angles to the parallel sides.
Assumptions
- All lengths in the same unit.
Limitations
- Results are rounded to 10 significant figures.
Frequently asked questions
What is the area of a trapezium?
Half the sum of the parallel sides × height.
Is a trapezium the same as a trapezoid?
Yes, in Indian and US usage respectively.
What is the median?
The average of the parallel sides.
Last reviewed on 3 October 2026. Found a mistake? Tell us.