data-ad-format="horizontal">



 
Perimeter of a triangle
Definition: The total distance around the outside of a triangle
Try this Drag any orange dot to resize the triangle. The perimeter is calculated as you drag.

How to find the perimeter of a triangle

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: where:
a,b and c are the lengths of each side of the triangle

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

While you are here..

... I have a small favor to ask. Over the years we have used advertising to support the site so it can remain free for everyone. However, advertising revenue is falling and I have always hated the ads. So, would you go to Patreon and become a patron of the site? When we reach the goal I will remove all advertising from the site.

It only takes a minute and any amount would be greatly appreciated. Thank you for considering it!   – John Page

Become a patron of the site at   patreon.com/mathopenref

Other triangle topics

General

Perimeter / Area

Triangle types

Triangle centers

Congruence and Similarity

Solving triangles

Triangle quizzes and exercises