Mulch calculator / Circular bed edging

Circular Bed Edging Calculator

Use the diameter you measured on site to count a circle or semicircle border. Choose which edges get edging, enter beds and measured openings, and get a net length in feet and meters.

Net border length

25.13 ft · 7.66 mExample only: one full circle, 8 ft diameter, no openings.

Worked example

Gross edge per bed: 25.13 ft · 7.66 m
Gross edge for all beds: 25.13 ft · 7.66 m
Measured openings: 0 ft · 0 m
Net length to plan: 25.13 ft · 7.66 m

Enter your measurements

Replace the example with one diameter shared by the identical beds. All lengths use the selected unit.

Boundary receiving edging

Full circle · entire circumference Semicircle · curved edge only Semicircle · curved edge plus straight side

Measured diameter Measure across the center Length unit Used for diameter and openings Identical beds Whole number Opening length across all beds Optional; enter a measured total

For a semicircle, use the straight distance from one end of the arc to the other. Openings are combined across all beds; leave zero only when the complete boundary gets edging.

Three edging boundaries: a full circle, a semicircle with only its curved arc edged, and a semicircle with both its curved arc and straight diameter edged. — The dotted line marks the measured diameter. Only the green boundary counts as edging; subtract any sections that will remain unedged.

How the length is calculated

Full circle: π × diameter
Semicircle arc: π × diameter ÷ 2
Semicircle arc and straight side: (π × diameter ÷ 2) + diameter
Net total = gross length per bed × bed count − measured openings

For one 8 ft diameter circle, π × 8 gives 25.13 ft of gross edge. Two identical circles need 50.27 ft before openings. For a semicircle with the same diameter, the curved arc is 12.57 ft; adding the straight 8 ft side gives 20.57 ft.

These are geometric lengths. The calculator does not add roll waste, overlap, connector pieces or stake spacing. Use the exact product instructions and your project plan for those choices. A diameter must be measured; a photo is not a scale reference.

Metric and US customary lengths convert using the international foot definition: 1 ft = 0.3048 m exactly. See NIST Handbook 44, 2026, Appendix C.

Circular edging questions

How much edging does a circular bed need?

Multiply the measured diameter by π. For an 8 ft diameter, the gross circumference is about 25.13 ft before subtracting any measured openings.

Does a semicircle include its straight side?

Choose curved edge only when edging follows the arc. Choose curved edge plus straight side when the diameter boundary also receives edging; that adds the measured diameter to half the circumference.

Can I subtract a gate or existing hard edge?

Yes. Enter the combined measured length across all beds that will not receive this edging. The calculator subtracts it from the gross total and rejects an opening length greater than that total.

Does the result include roll waste, overlaps or stake spacing?

No. It reports the measured border length only. Apply any waste, roll joins, overlaps, connectors or stake spacing from the instructions for the exact edging product and your project plan.

Continue the edging plan

Need mulch quantity for a circular bed with an open center? Measure both diameters in the circular mulch border calculator to estimate ring volume and inner and outer edging lengths.

Plan mulch quantity and roll cuts Count stakes from product spacing Convert other measured lengths