Perimeter of a trapezoid ("trapezium" in British usage)
Definition: The total distance around the outside of a trapezoid
Try this Drag any orange dot to resize the trapezoid. The perimeter is calculated as you drag.

How to find the perimeter of a trapezoid

Like any polygon, the perimeter is the total distance around the outside, which can be found by adding together the length of each side. Or as a formula:

perimeter = a+b+c+d where:
a,b,c,d are the lengths of each side

In the figure above, drag any orange dot to resize the trapezoid. From the side lengths shown, calculate the perimeter and verify your result matches the formula at the top of the diagram.

Coordinate Geometry

In coordinate geometry, if you know the coordinates of the four vertices, you can calculate various properties of it, including the area and perimeter. For more on this, see Trapezoid area and perimeter (Coordinate Geometry)

Things to try

  1. In the figure above, click on "hide details".
  2. Drag the four orange dots to reshape the trapezoid.
  3. Calculate the perimeter.
  4. Click "Show details" to check your answer.
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Other polygon topics


Types of polygon

Area of various polygon types

Perimeter of various polygon types

Angles associated with polygons

Named polygons