Trapezoid Calculator

A trapezoid is a quadrilateral with at least one pair of parallel sides under the inclusive convention. Some textbooks use an exclusive definition that requires exactly one pair and therefore excludes parallelograms. The parallel sides used by this calculator are the bases a and b, and h is their perpendicular separation.

Use the formula A = (a + b) / 2 x h. Add the two parallel bases, divide by 2, then multiply by the perpendicular height. A trapezoid with 6 ft and 10 ft bases and a 4 ft height has an area of 32 sq ft. Results are displayed to four decimal places.

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.

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.

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.