What formulas does this calculator use?

Area = (π × radius²) ÷ 2; Perimeter = π × radius + 2 × radius.

Where are semicircle shapes commonly used?

Arched windows and doorways, and certain sports field markings.

Semicircle Calculator - CalculatorLabs.net

Q: What is a semicircle?

Exactly half of a circle, cut along its diameter.

Semicircle Calculator

Calculate the area, perimeter, and arc length of a semicircle.

What Is the Semicircle Calculator?

A semicircle is exactly half of a circle, cut along its diameter. This calculator finds its area, curved arc length, and full perimeter (the arc plus the straight diameter edge) from the radius.

A semicircle is half of a full circle

Formula Used

Area = ½ × π × r²
Arc Length = π × r
Perimeter = π × r + 2r

r is the radius of the full circle the semicircle was cut from. The perimeter includes both the curved edge and the flat diameter edge.

How to Use This Calculator

Enter the radius of the semicircle.
Click Calculate to see the area, arc length, and full perimeter.

Worked Example

A semicircle with a radius of 10 has an area of 0.5×π×10² ≈ 157.08 square units, an arc length of π×10 ≈ 31.42 units, and a total perimeter of 31.42 + 20 = 51.42 units.