Semicircle Calculator
Calculate the area and perimeter of a semicircle from its radius.
- Perimeter (arc + diameter)
- 25.708
Formula: A = (π × r²) / 2
About Semicircle Calculator
Semicircle Calculator is a free online calculator that gives you an instant, accurate result as you type. Calculate the area and perimeter of a semicircle from its radius.
The calculation uses the standard formula A = (π × r²) / 2 and updates live with every change to the inputs. Everything runs client-side in your browser — fast, private, and free to use as often as you like.
The perimeter of a semicircle includes the straight diameter edge, so it is πr + 2r, not just half a circumference.
Frequently Asked Questions
Is Semicircle Calculator free to use?
Yes. Semicircle Calculator is completely free, with no sign-up, no downloads, and no usage limits. You can use it as many times as you like on any device with a web browser.
How accurate is this calculator?
The calculator applies the standard formula (A = (π × r²) / 2) with full floating-point precision and rounds only the displayed result. For most practical purposes the results are exact.
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