Trapezoid Area Calculator
Compute the area of a trapezoid from its parallel sides and height: A = ½(a + b) × h.
Calculator
Use the Trapezoid Area Calculator
Result
—
Formula
A = ½ × (a + b) × h
Step-by-step
- 1
Enter both parallel sides
a and b are the parallel sides.
- 2
Enter the height
Perpendicular distance between them.
Worked example
Example input: a: 6, b: 10, h: 4
Result: 32
Related tools
- Parallelogram Area
base × height.
Frequently asked questions
What is the trapezoid area formula?
A = (a + b) / 2 x h — average the two parallel sides, then multiply by the perpendicular height. Sides 6 and 10 with height 4 give 32 square units, matching the example.
Why average the two parallel sides?
The midline of a trapezoid is half the sum of its bases, so the shape behaves like a rectangle whose width is that average. Stretch a slanted side and the average keeps the middle geometry intact.
Which sides do a and b stand for?
The two parallel sides — the true bases at top and bottom. The slanted legs never enter the formula, only the distance measured straight across between the bases does.