Math
Trapezoid Calculator
Calculate the area, median, and perimeter of a trapezoid from its two parallel sides, height, and (optional) leg lengths.
Trapezoid dimensions
Area
28
- Median
- 7
- Perimeter
- 24
Frequently Asked Questions about the Trapezoid Calculator
What is a trapezoid?
A trapezoid is a four-sided shape with exactly one pair of parallel sides. Those parallel sides are called the bases (a and b), and the perpendicular distance between them is the height (h). In British English the same shape is called a trapezium.
How do you find the area of a trapezoid?
Use the formula A = (a + b) / 2 x h. Add the two parallel bases, divide by 2, then multiply by the perpendicular height. For example, a trapezoid with bases 6 ft and 10 ft and a height of 4 ft has an area of (6 + 10) / 2 x 4 = 32 sq ft. The calculator applies this formula and rounds to 6 decimal places.
What is the median of a trapezoid?
The median is the line segment that joins the midpoints of the two non-parallel legs. Its length equals the average of the two bases: (a + b) / 2. Because of that relationship, area also equals median x height, so the median is a handy shortcut when you already know it.
Why does perimeter require all four sides?
Perimeter sums every side: a + b + c + d. Knowing the two parallel bases and the height does not fix the lengths of the non-parallel legs (c and d), since many different leg lengths can produce the same area. Enter both legs to get the perimeter result.
Does the trapezoid have to be isosceles?
No. The area formula A = (a + b) / 2 x h works for any trapezoid, whether it is isosceles, right-angled, or scalene. You only need the two parallel bases and the perpendicular height. Perimeter still requires the actual leg lengths c and d regardless of shape type.