Instantly compute the area, arc length, and perimeter of a semicircle online.
Perimeter (P) • Arc Length
Area (A)
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Step 01
Input the radius (r) or optionally the diameter (d) of the semicircle.
Step 02
Instantly get the area, arc length, and total perimeter.
Step 03
Expand the details to review the mathematical formula breakdown.
| Property | Formula | Description |
|---|---|---|
| Area (A) | A = (π · r²) / 2 | Half of the full circle's area. |
| Arc Length (b) | b = π · r | Length of the curved edge. |
| Perimeter (P) | P = π · r + d | Arc length plus straight diameter. |
Double-check whether your blueprint specifies the radius (center to edge) or the full diameter.
Remember that the total perimeter includes the straight flat edge in addition to the curved arc.
Ensure all dimensional inputs use the exact same unit of measurement (e.g., inches or meters).
The calculator uses standard high-precision floating-point Pi calculations internally.
Ideal for garden layouts, archways, tabletops, and material carpet cuts.
Use our online tool as a fast cross-check for homework or design drafts.
Legal Disclaimer: Calculators serve as educational reference guides.
The area is half of a full circle: A = (π · r²) / 2.
The perimeter is the curved arc length plus the straight diameter: P = π · r + d.
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