Landscape Edging Calculator

How it works

The length of edging is the distance around the bed. A rectangle's perimeter is twice the length plus the width; a circle's is π times the diameter; for any other outline the custom option adds up the lengths of the runs entered, which may be the sides of an irregular bed or a single straight run along a path.

A waste allowance is added for overlaps where pieces join, for cuts at corners and for the extra length a curve takes up in practice. Dividing the length with waste by the length of one piece and rounding up gives the coils or strips.

Stakes are counted along the actual perimeter, without the waste allowance: the perimeter divided by the stake spacing, rounded up, which is one stake per interval around a closed outline.

Formula

rectangle: P = 2 × (L + W)
circle:    P = π × D
custom:    P = sum of side lengths
linear ft  = P × (1 + waste % ÷ 100)
pieces     = ⌈ linear ft ÷ piece length ⌉     (20, 40, 60 ft coils; 8 ft strips)
stakes     = ⌈ P ÷ stake spacing ⌉   (closed outline)
open runs: stakes = Σ (⌈ run ÷ stake spacing ⌉ + 1)

Example

A 20 ft × 10 ft bed has a perimeter of 2 × (20 + 10) = 60 ft. With a 5% waste allowance that is 63 ft of edging, or 4 coils of 20 ft (63 ÷ 20 = 3.15). Stakes every 3 ft around the 60 ft outline come to 20.

A circular bed 8 ft across has a perimeter of π × 8 = 25.13 ft, or 26.39 ft with 5% waste: 2 coils of 20 ft and 9 stakes at 3 ft.

Assumptions and limitations

• Stakes are counted for a closed outline, one per interval. For custom lengths entered as separate open runs, each run is staked on its own and gets one more stake for its second free end.
• The waste allowance is a judgement: 5% suits straight runs with few joins; curves, many corners or overlapping joins take more. Connectors and the overlap at joins are not counted separately.
• Coil and strip lengths are nominal. Stake spacing is a typical figure, not a specification; edging kits vary in how many stakes they include, and the product's instructions take precedence.
• A circle is measured by its diameter across the widest point. For an oval or free-form bed, a hose or tape laid along the edge and entered as custom runs gives a closer figure.

Frequently asked questions