Perimeter/circumference for 10 shapes with formula and diagram.. Perimeter Calculator is a free online tool from the ToolsRift Math Calculators collection. It runs entirely in your browser — nothing to install, no signup, and your data never leaves your device.
Choose the shape, enter its side lengths or radius, and the perimeter or circumference is calculated instantly with the formula displayed.
Perimeter is the total distance around a straight-sided shape; circumference is that same distance for a circle, found with 2 × π × r.
Yes — enter length and width and it returns 2 × (length + width) as the perimeter.
Square, rectangle, triangle, circle, parallelogram, trapezoid, rhombus, regular polygon and more, each with its own formula.