Area of a Trapezoid Calculator
Average the two parallel sides, then multiply by the height between them. Two copies of a trapezoid, one flipped, make a parallelogram of base a + b.
A = ½ (a + b) × h
Perimeter: Add the two bases and both slanted legs
Area of the trapezoid
40ft²
- Perimeter
- see note
- Average base = (6 + 10) / 2 = 8
- A = 8 × 5 = 40 ft²
Area in other units
| m² | 3.7161 |
| cm² | 37,161.2 |
| ft² | 40 |
| in² | 5,760 |
| yd² | 4.4444 |
| acres | 0.000918 |
| hectares | 0.000372 |
How to find the area of a trapezoid
Formula: A = ½ (a + b) × h. Perimeter: Add the two bases and both slanted legs.
- Measure every length in the same unit. Mixing feet and inches is the most common mistake; convert first (6 in = 0.5 ft).
- Put the numbers into the formula above. The calculator shows each substitution with your numbers.
- Area comes out in square units (ft², m²). If you need a different unit, open "Area in other units".
Questions people ask
Is a trapezium the same as a trapezoid?
In US English a trapezoid has one pair of parallel sides; in British English that shape is called a trapezium. The area formula is the same.
Does the trapezoid need to be symmetric?
No. The formula works for any trapezoid as long as h is the perpendicular distance between the parallel sides.
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