PERIMETER CALCULATOR

Rectangle: P = 2(L + W).

Square: P = 4s.

Triangle: P = a + b + c.

Circle: circumference C = 2πr.

Parallelogram: P = 2(a + b).

Trapezium: P = a + b + c + d.

Perimeter is the total distance around the outside of a shape.

For circles, this outside distance is called circumference.

This calculator finds the total outside length of common 2D shapes.

For circles, it calculates circumference.

It supports rectangles, squares, triangles, circles and trapeziums.

Perimeter answers use normal length units, not square units.

Choose the shape first, then enter the side lengths requested.

For a circle, enter the radius to calculate circumference.

For a trapezium, enter all four side lengths.

Choose rounding, then press SOLVE or Enter.

Rectangle: 2(12 + 4) = 32.

Square: 4 × 6 = 24.

Triangle: 7 + 8 + 9 = 24.

Circle: 2π × 3 ≈ 18.85.

Perimeter uses normal length units such as cm, m or mm.

It is not squared, because it is a distance around an edge.

Use the same length unit for every side in the calculation.

Area uses square units; perimeter uses length units.

POPULAR PERIMETER SEARCHES

Perimeter calculator for shapes

Rectangle perimeter calculator

Triangle perimeter calculator with working

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Trapezium perimeter calculator

Parallelogram perimeter calculator

GCSE perimeter formulas

Shape perimeter formulas

Students use it for GCSE perimeter questions and KS2 or KS3 homework.

Teachers use it to check examples and show formula substitution.

Tutors use it for shape formula revision and circumference practice.

Parents can support perimeter and circle circumference homework.

Perimeter belongs in the Teletext geometry calculators section.

What units does it use? The answer uses the same length unit.

Is circumference perimeter? Yes, circumference is circle perimeter.

Does circle mode use diameter? This tool uses radius.

Can it show working? Yes, Screen 1 shows formula and substitution.