Perimeter Calculator

Find the perimeter of rectangles, squares, triangles, circles, ellipses, sectors and regular polygons.

Shape	Rectangle
Length	8
Width	5
Unit (optional)	cm

Shape

Length

Width

Unit (optional)

Rectangle perimeter

26cm

Perimeter = 2 × (length + width) = 26 cm.

Your rectangle

1
Formula
P = 2 × (length + width)
2
With your measurements
Length = 8, Width = 5 → 26 cm

About the Perimeter Calculator

Perimeter is the total distance around a shape. It's what you need for fencing, skirting boards, trim and borders. A circle's perimeter is called its circumference. An ellipse has no exact simple formula; Ramanujan's approximation used here is accurate to within a tiny fraction of a percent.

The formula

Rectangle: P = 2(l + w); Circle: C = 2πr

Worked example

Garden 12 m × 7 m

P = 2 × (12 + 7) = 38 m of fencing

Questions people ask

Why does my triangle show an error?

Any two sides must add up to more than the third side, or the triangle can't close.

Is circumference the same as perimeter?

Yes, for a circle.