Perimeter of a Semicircle Calculator

Summary

Enter a radius or diameter to instantly get the full perimeter of a semicircle — curved arc plus straight diameter — with step-by-step working.

How it works

1. Choose whether you are entering the radius or the diameter.
2. Type your measurement into the input field.
3. Select the unit of measurement (mm, cm, m, in, or ft).
4. Click "Calculate" to apply the perimeter formula.
5. The arc length, diameter, and total perimeter are shown instantly with step-by-step working.

Use cases

• Geometry homework involving semicircle boundary length.
• Architecture — calculating the trim length for a half-circle arch or window.
• Landscaping — estimating edging needed for a half-circle garden bed.
• Engineering problems with semicircular sections or channels.
• Woodworking — measuring the cut perimeter of a semicircular piece.
• Fencing or framing a half-circle feature in construction projects.
• Verifying manual semicircle perimeter calculations quickly.

Frequently Asked Questions