How to calculate landscape fabric rolls
Measure the length and width of your area and check the dimensions of the fabric roll. This tool compares strips running along either side and allows for overlap and the number of complete strips cut from each roll. Simply dividing the area by the area of a roll may underestimate the rolls required. This is a geometric estimate for a rectangular flat area without lengthwise joins.
Example: an 8 × 5 m area, a 2 × 25 m roll, 15 cm overlap and no extra allowance. Three 8 m strips need 24 linear metres, which fit into one 25 m roll.
Results are estimates and depend on the supplied values.
How much landscape fabric should you buy?
Measure the area and the roll
Enter the actual dimensions of your rectangular area and the roll you intend to purchase. Area alone is not enough to work out exact roll counts: cutting may leave offcuts that cannot form a complete strip.
Area (m²) = area length (m) × area width (m)
Why overlap changes coverage
Neighbouring strips share a band of material. Each additional strip therefore covers less new width than the nominal roll width. Use the overlap specified for your fabric and installation instead of assuming one value fits all products.
Covered width = strips × roll width − (strips − 1) × overlap
How roll counts are calculated
Each strip is assumed to be cut in one piece, with no lengthwise joins. We count the complete strips that fit along the roll and round the number of rolls up. A chosen allowance reserves extra material too.
Strips per roll = floor(roll length ÷ strip length)
Why rotating strips can save fabric
For an 8 × 5 m area, a 2 × 25 m roll and 15 cm overlap, you can use three 8 m strips (24 linear metres) or five 5 m strips (25 linear metres). Both layouts need one roll without extra allowance, but the former uses less linear material.
8 × 5 m · 2 × 25 m roll · 0.15 m overlap → 3 strips × 8 m = 24 m
Important: this tool plans rectangular flat areas with unjoined, full-length strips. It does not account for lengthwise joins, obstacles, slopes, edge returns, advanced offcut reuse or specialised fixing requirements. Consult the manufacturer’s instructions.
Frequently asked questions
How much landscape fabric do I need for 40 m²?
It depends on the shape of your area, the roll dimensions, overlaps and strip layout. Two areas of 40 m² can need different cuts and different numbers of rolls.
Why do I need length and width, rather than just area?
Complete cuts need a known strip length. An 8 × 5 m plot cannot be cut in the same way as a 20 × 2 m plot even though both cover 40 m².
Why can more overlap mean more rolls?
Overlap uses some of the roll width without covering new ground. You may need an additional strip for the same area, which can increase total roll demand.
Can I join strips end to end?
Depending on the material and project, yes, but this tool does not count those joins. A layout is flagged unavailable when a strip is longer than the roll.
How much geotextile do I need under gravel?
For a flat rectangular plot, this tool estimates strips and overlap. For a wrapped drainage trench or a sloping surface, you must also account for sides, returns and joins in a separate plan.
Does extra allowance increase the covered area?
No. Allowance reserves extra material for losses and cuts; it does not increase the dimensions of the area or strips.
Plan other garden materials too
If you are laying gravel over the fabric or building a drainage trench, these calculators estimate the other materials separately without mixing up measurements.
Calculate gravel volume and weight
Calculate drainage trench materials