Calculation details
Planning estimate only, not financial, tax, or legal advice. Verify assumptions and current rules before making decisions.
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What does this calculator estimate?
A semicircle is half a circle; its area is half the circle's area and its perimeter includes the diameter.
- Area = πr²/2.
- Perimeter = πr + 2r.
- Common in arches, half-round tables, and layouts.
What does this calculator estimate?
How this calculator works
Formula
Area = (π × r²)/2; perimeter = π × r + 2r (arc plus the straight diameter).
Worked example
r = 4 m: area ≈ 25.13 m², perimeter ≈ 20.57 m.
Assumptions to verify
- Standard geometric or arithmetic definitions apply.
- Inputs use the units you choose.
- Results are estimates, not professional advice.
Frequently asked questions
Cite this tool
BoringToolsKit. “Semicircle Calculator.” boringtoolskit.com/semicircle-calculator/ (reviewed 2026-08-27). Free to reference in articles, syllabi, and answer posts with a link.
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