Rectangle Perimeter Calculator
Compute the perimeter of a rectangle: P = 2 × (length + width).
Calculator
Use the Rectangle Perimeter Calculator
Result
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Formula
P = 2 × (length + width)
Step-by-step
- 1
Enter length and width
Both must be positive.
- 2
Read the perimeter
Distance all the way around.
Worked example
Example input: a: 8, b: 3
Result: 22
Related tools
- Rectangle Area
l × w.
Frequently asked questions
What is the rectangle perimeter formula?
P = 2 × (length + width). Opposite sides are equal, so adding one length and one width and doubling counts all four edges exactly once. A 7 × 4 rectangle wraps to 22 units.
How do perimeter and area differ?
Perimeter multiplies the sum of the sides by 2 and measures distance; area multiplies length × width and measures surface. Two equal-area rectangles can differ in perimeter — 6 × 8 and 4 × 12 both cover 48 square units, but their perimeters are 28 versus 32 units.
What if my shape is not a rectangle?
Then the formula changes: squares use 4 × side, circles use 2πr, triangles add three sides together. Use the shape-specific calculator — this page assumes exactly two distinct side lengths.