Trapezoid area calculator
Calculator
The calculator needs JavaScript. The tables below give the same numbers for common cases.
How it is worked out
- Median = (a + b) ÷ 2 = 6.5.
- Area = median × height = 6.5 × 3 = 19.5.
| Inputs | Answer |
|---|---|
| Base a: 8; Base b: 5; Height: 3 | The trapezoid area is 19.5. |
| Base a: 12; Base b: 7; Height: 4.5 | The trapezoid area is 42.75. |
| Base a: 10; Base b: 10; Height: 6 | The trapezoid area is 60. |
How to use it
A trapezoid has two parallel sides (bases) a and b. Its area is the average of the bases times the height: ½ × (a + b) × h. The average of the bases is also the length of the median, the segment joining the midpoints of the legs.
The height is the perpendicular distance between the bases, not the length of a slanted leg.
Frequently asked questions
What is the area of a trapezoid with bases 8 and 5 and height 3?
½ × 13 × 3 = 19.5.
What is the median of a trapezoid?
The average of the two bases, (a + b) ÷ 2.
Is a parallelogram a trapezoid?
Under the inclusive definition yes, because it has two pairs of parallel sides; some textbooks require exactly one pair.
Method: standard arithmetic shown step by step; no outside data is used. Checked 2026-11-12.
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