What is the area formula for a trapezoid?

Area equals one-half times the sum of the two parallel bases times the height (A = 1/2 · (a + b) · h).

What is the midsegment of a trapezoid?

The midsegment, or median, equals the average of the two parallel bases, (a + b) / 2.

Why do the legs only change the perimeter?

The area depends only on the two parallel bases and the height. The legs affect the perimeter but not the enclosed area.

Trapezoid Calculator

Area, perimeter and midsegment of a trapezoid.

Trapezoid calculator

Enter the top base, bottom base and height to get the trapezoid’s area (½·(a + b)·h) and midsegment ((a + b)/2). Add the two legs to get the perimeter. Works for any trapezoid (trapezium) and updates instantly in your browser.