Trapezoid Area Calculator
Mean of the parallel sides, times the height.
Work out Trapezoid Area. Mean of the parallel sides, times the height. Handles the case the formula sheet skips.
The perpendicular distance, not the slanted side.
Optional, for the perimeter.
Area
32
midsegment 8 × height 4
Area is the average of the two parallel sides times the height: ((a + b) ÷ 2) × h. That average is the midsegment — the line joining the midpoints of the slanted sides — so a trapezoid has exactly the area of a rectangle with the midsegment as its base. The height must be the perpendicular distance between the parallel sides, not the length of a slanted side. Using the slant is the commonest error here and always overstates the area.
How the Trapezoid Area Calculator works
Enter both parallel sides and the perpendicular height between them. The area equals a rectangle built on the midsegment — the average of the two parallel sides — which is a more intuitive way to see it than the formula suggests.
Also known as: trapezium area calculator · area of a trapezoid formula · midsegment calculator · trapezoid perimeter calculator
Frequently asked questions
What is the area of a trapezoid?
((a + b) ÷ 2) × h, where a and b are the parallel sides and h is the perpendicular distance between them.
What is the midsegment?
The line joining the midpoints of the two slanted sides. Its length is the average of the parallel sides, so a trapezoid has exactly the same area as a rectangle with the midsegment as its base.
Which measurement is the height?
The perpendicular distance between the parallel sides — not the length of a slanted side. Using the slant is the commonest mistake here and always overstates the area.
Is a trapezoid the same as a trapezium?
In British usage, yes. In American usage a trapezium historically meant a quadrilateral with no parallel sides at all, which is the opposite. The shape here is the one with exactly one pair of parallel sides.
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