Landscape Fabric Calculator

A landscape fabric calculator divides your bed area by the coverage of one roll. A standard roll is 3 ft wide by 100 ft long, which is 300 sq ft. A 30 × 10 ft bed is exactly 300 sq ft, so it takes 1 roll, or 2 rolls if you add 10% for overlaps.

The formula in plain words

Find the area of the bed. Divide it by 300. Round up to a whole roll, since stores sell the roll as a unit.

The 10% waste box is for the seams. Fabric strips are laid side by side with a 6 inch overlap, and every overlap uses material twice. Ten percent is a reasonable allowance for a plain rectangular bed. Curved edges and corners use more.

Worked examples

Example 1, the default: 30 ft by 10 ft, $40 per roll.

• Area: 30 × 10 = 300 sq ft
• Without waste: 300 ÷ 300 = 1 roll, $40
• With waste: 300 × 1.10 = 330 sq ft, 330 ÷ 300 = 1.1, rounded up to 2 rolls, $80

That one tick of the box doubles the order, because the bed is exactly one roll to begin with.

Example 2, a bed where the overlaps clearly matter: 30 ft long and 10 ft wide, laid with a 3 ft roll and 6 inch overlaps.

• The first strip covers 3 ft of width, and each strip after that adds 2.5 ft
• 3 + 2.5 + 2.5 + 2.5 = 10.5 ft, so you need 4 strips
• 4 strips × 30 ft = 120 ft of fabric from a 100 ft roll, which is 2 rolls

The calculator’s waste option gets the same answer for this bed. Without it you would be 20 ft short.

Rolls by bed size

Bed size	Area	Rolls	With 10% waste
15 × 5 ft	75 sq ft	1	1
25 × 8 ft	200 sq ft	1	1
30 × 10 ft	300 sq ft	1	2
40 × 12 ft	480 sq ft	2	2
50 × 10 ft	500 sq ft	2	2
60 × 20 ft	1,200 sq ft	4	5

How to measure

Measure the length and width of each bed. For curved beds, measure the longest length and the average width, or treat the bed as the smallest rectangle that contains it and accept some spare fabric.

If you have several beds, add their areas together. If you can split them, the strips may come off a single roll with less left over.

Beds wider than the roll need more strips, so think about the direction of the strips. Run the strips along the longer side so there are fewer seams.

Common mistakes

• Putting the seams where water runs. Overlap with the higher strip on top so water flows over the seam instead of into it.
• Skipping the overlap in the plan, then running out of fabric one strip from the end.
• Leaving cut edges frayed at the border. Tuck them under the edging or bury them.
• Laying fabric under a bed you plan to replant often. It will tear every time you dig.
• Leaving fabric exposed. Sun breaks it down, so cover it with mulch or stone.

Woven and non-woven fabric

Woven fabric looks like a tight mesh of plastic strips. Non-woven fabric looks like felt. Woven types are common under stone and gravel, where water has to drain through the layer. Either way, look at the label for the roll width, since some rolls are 4 ft or 6 ft wide, and recalculate the strips if yours differs from the 3 ft assumed here.

Planting through fabric

Cut an X where each plant goes, fold the flaps back, set the plant, and fold them over the stem. Keep the X small so weeds have little room. For a bed that gets new plants every year, think about a different weed control, such as mulch alone. Stone over fabric is better for permanent paths and borders.

Related calculators

The cover layer on top of the fabric comes from the mulch calculator, the landscape rock calculator, or the river rock calculator. The gravel base calculator covers a path or patio base that fabric might sit under.