The calculation, without hidden assumptions
One calculator for the common perimeter jobs: rectangles, squares, triangles from three sides, and circles. Pick the shape, enter its dimensions, and the result shows the exact expression used so you can order the right amount of edging, trim or fencing and check the arithmetic.
How to use this calculator
Choose the shape you are measuring.
Enter its dimensions in one consistent unit.
Read the perimeter and the substituted formula.
Where people use it
- •Planning edging, trim or fencing lengths
- •Geometry homework checks
- •Estimating the border of a rectangular or round garden bed
Example: 6 × 4
A 6 × 4 rectangle has perimeter 2 × (6 + 4) = 20 in the same unit as the sides.
What the result does not assume
- •Irregular shapes need separate measured segments that are added together.
- •For a circle the first field is the radius, and the result is the circumference.
Frequently asked questions
Is circumference a perimeter?+
Yes; it is the perimeter of a circle.
How do I find the perimeter of a triangle?+
Add the three side lengths. If you only know two sides of a right triangle, solve the third with the Pythagorean calculator first.
Does perimeter depend on the area?+
Not directly. Different shapes can enclose the same area with very different perimeters, so always calculate the one you need.
Semantic next steps
Continue the calculation
These links move to a different input, formula or project stage rather than a keyword variation of this page.
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Keep the result connected to the real job
MAXScanner keeps the formula and assumptions beside the result so you can verify the number before using it in a drawing, estimate, specification, worksheet or document. Where a supplier, manufacturer, drawing or applicable standard owns a requirement, that source remains authoritative.