Perimeter Calculator
Compute the perimeter of rectangles, triangles, and circles.
Perimeter
40 units
If units are feet
13.33 yards
The boundary measure
Perimeter adds the edges: 2(l + w) for rectangles, three sides for triangles, 2πr for circles. It prices fencing, baseboards, trim, and track lengths — anywhere the cost follows the outline rather than the area.
Same area, different perimeter
A 1×16 rectangle and a 4×4 square both cover 16 square units, but their perimeters are 34 and 16. Circles minimize perimeter for a given area — why bubbles are round and why long skinny rooms cost more baseboard per square foot.
Frequently asked questions
- How does the Perimeter Calculator work?
- Compute the perimeter of rectangles, triangles, and circles.
- Is the Perimeter Calculator free to use?
- Yes. The Perimeter Calculator is completely free, runs entirely in your browser, and requires no account or sign-up. Your inputs never leave your device.
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