Perimeter Calculator
Calculate the perimeter of a shape by selecting a shape and entering your measurements in any unit, metric or imperial. See formulas for each shape below.
Rectangle Perimeter Calculator
Square Perimeter Calculator
Trapezoid Perimeter Calculator
Parallelogram Perimeter Calculator
Triangle Perimeter Calculator
Circle Circumference Calculator
Ellipse Circumference Calculator
Sector Perimeter Calculator
Regular Polygon Perimeter Calculator
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How to Find the Perimeter of a Shape
Perimeter is the length of the outer edge or boundary of a 2-dimensional shape and is expressed in units of length, such as inches or feet. Perimeter is often found by measuring each edge of a shape and adding the edge lengths together to get the total length. The outer edge of a circle or ellipse is referred to as the circumference.
When measuring use the same unit of measurement for each edge, and use our length unit conversion calculators to convert all measurements to the same length if needed.
Square Perimeter Formula
P = 4a
a = edge length
Rectangle Perimeter Formula
P = 2l + 2w
l = length
w = width
Trapezoid Perimeter Formula
P = a + b + c + d
a = base a
b = base b
c = side c
d = side d
Parallelogram Perimeter Formula
P = 2a + 2b
a = side
b = base
Triangle Perimeter Formula
P = a + b + c
a = edge a
b = edge b
c = edge c
Circle Perimeter Formula
P = 2πr
r = radius
Try our circumference calculator to solve using the radius, diameter, or area.
Ellipse Perimeter Formula
P ≈ π[3(a + b) – (((3a + b))(a + 3b))]
a = axis a
b = axis b
Sector Perimeter Formula
P = 2r + ((2θπr) ÷ 360)
r = radius
θ = angle
Regular Polygon Perimeter Formula
P = an
a = edge length
n = number of sides
Use our area calculator to find the area of a shape.
