FinanceCalcs
Perimeter Calculator
The perimeter is the total distance around the outside of a shape. Choose any shape, enter the measurements, and get the perimeter with the formula and full working shown.
Step-by-Step Working
"Perimeter vs area: perimeter measures around the edge (like fencing a garden), area measures the space inside (like turf to fill it). Both use the same shape — completely different answers!"
Perimeter formulas at a glance
| Shape | Formula |
|---|---|
| Square | P = 4 × s |
| Rectangle | P = 2 × (l + w) |
| Triangle | P = a + b + c |
| Circle | C = 2πr = πd |
| Regular polygon (n sides) | P = n × s |
| Parallelogram | P = 2 × (a + b) |
Quick Questions
What’s the difference between perimeter and circumference?
They’re the same thing — just different words! Perimeter is used for straight-sided shapes. Circumference is the word specifically for the perimeter of a circle. The formula is C = 2πr, where r is the radius and π ≈ 3.14159.
What are real-life uses of perimeter?
Perimeter is everywhere: fencing a garden or field, adding trim or border around a room, framing a picture, measuring how far you walk around a track, or working out how much ribbon you need to go around a gift box. Any time you’re measuring around the outside of something, that’s perimeter.
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