Math Calculators

Semicircle Calculator

Calculate a semicircle's area and perimeter from its radius, in the unit of your choice.

Area —

Perimeter —

About the Semicircle Calculator

A semicircle is half of a circle, split along its diameter. Its area is half the full circle's area, and its perimeter adds the curved arc to the straight diameter. The radius, area and perimeter each have their own unit selector, so you can convert between them freely.

Formulas: Area = πr²/2 · Perimeter = πr + 2r