Trapezoid Calculator for Area, Perimeter, Sides, Diagonals and Angles

Updated By Unit Conversion Plus

Solve a trapezoid from its parallel bases, perpendicular height and horizontal offset.

Trapezoid measurements

For the top base to remain above the lower base, use an offset from 0 to a − b.

Trapezoid formulas

Area = (a + b)h ÷ 2 · Midline = (a + b) ÷ 2

The offset locates the shorter top base and allows both legs, diagonals and base angles to be calculated.

Isosceles trapezoid

An isosceles trapezoid has equal legs. With bases a and b, its top base is centred, so x = (a − b) ÷ 2.

Frequently asked questions

Which sides are the bases?

The bases are the parallel sides.

Can the offset be negative?

A negative offset describes an overhanging top base, but this calculator focuses on the common contained configuration.