Perimeter Calculator

Perimeter is the total continuous boundary length surrounding a two-dimensional geometric shape. This free Perimeter Calculator computes the exact per

Mathematics

Geometric Polygon

Dimension 1 (Length / Side / Radius / a)

Dimension 2 (Width / Side b)

Dimension 3 (Side c for Triangle)

Formula & Methodology

Rectangle: P = 2 × (Length + Width) Square: P = 4 × Side Triangle: P = Side a + Side b + Side c Circle (Circumference): P = 2 × π × Radius

To compute perimeter: 1. Identify the geometric shape and trace its entire external boundary path. 2. For polygons (rectangles, squares, triangles), sum the linear lengths of all individual enclosing sides. 3. For curved circles, multiply the radius by 2π (Circumference = 2πr).

Perimeter (Rectangle)

Overview

Perimeter is the total continuous boundary length surrounding a two-dimensional geometric shape. This free Perimeter Calculator computes the exact perimeter for rectangles, squares, triangles, and circles.

Perimeter calculations are essential in fencing property boundaries, framing paintings, installing floor baseboards and crown molding, and sizing running track lengths.

Worked Examples

Example 1: Fencing a 10m × 6m Yard

Shape: Rectangle, Length = 10, Width = 6

Formula: 2 × (10 + 6) = 2 × 16 = 32 meters.

Final Answer: 32.00 linear units

Example 2: Framing a Square Painting (Side 15 inches)

Shape: Square, Side = 15

Formula: 4 × 15 = 60 inches.

Final Answer: 60.00 linear units

Example 3: Triangle Perimeter (Sides 10, 6, 8)

Shape: Triangle, a = 10, b = 6, c = 8

Formula: 10 + 6 + 8 = 24.

Final Answer: 24.00 linear units

Shape	Dimensions	Formula	Perimeter Result
Rectangle	10 × 6	2(10 + 6)	32.00
Square	Side = 10	4 × 10	40.00
Triangle	10, 6, 8	10 + 6 + 8	24.00
Circle	Radius = 5	2 × π × 5	31.42
Rectangle	25 × 15	2(25 + 15)	80.00

Shape

Dimensions

Formula

Perimeter Result

Rectangle

10 × 6

2(10 + 6)

32.00

Square

Side = 10

4 × 10

40.00

Triangle

10, 6, 8

10 + 6 + 8

24.00

Circle

Radius = 5

2 × π × 5

31.42

Rectangle

25 × 15

2(25 + 15)

80.00

Frequently Asked Questions

What is the difference between perimeter and area?

Perimeter measures the one-dimensional distance around the outside edge (in linear units like feet or meters). Area measures the two-dimensional surface space inside (in square units like ft² or m²).

Can two shapes have the same perimeter but different areas?

Yes! An 8×2 rectangle has a perimeter of 20 and an area of 16. A 5×5 square also has a perimeter of 20, but an area of 25. For any given perimeter, a circle encloses the maximum possible area.

How do you calculate perimeter for irregular polygons?

Measure each exterior side individually and sum them together: Perimeter = s₁ + s₂ + s₃ + ... + sₙ.

What is circle perimeter called?

The perimeter of a circle is specifically called its circumference.

Can perimeter ever be negative or zero?

No. Physical boundaries must have strictly positive lengths.