Landscape Fabric Calculator

Divide your bed's area by the roll's effective coverage: its width minus the seam overlap, times its length. This calculator does that directly: enter your bed size, pick a roll width and length, and it works out the roll count including the overlap loss, so you don't come up short at the last strip.

About 4 to 6 inches at every seam, per Utah State University Extension's Water-Wise Landscaping guidance. That overlap is what keeps a gap from opening between strips as the fabric settles; skip it and weeds find the seam line within a season.

Because the overlapped strip isn't new ground: it's the same few inches covered twice, once by each adjacent strip. A 3 ft roll with a 4-inch overlap only adds about 2 ft 8 in of new coverage per strip after the first, not the full 3 ft the roll is labeled. This calculator subtracts the overlap before dividing your area by the roll, so the roll count already accounts for it.

Roughly one pin every 12 to 18 inches along every edge and seam, per common landscape fabric manufacturer installation guidance: tighter than the open middle of the bed, since edges and seams are where wind and foot traffic lift a loose corner first. This calculator estimates a pin range from your bed's perimeter plus the seams created by however many strips it takes to cover the area.

Commonly 3, 4, 6 and 12 feet, with the 12 ft width mostly sold for larger commercial jobs. Length varies by manufacturer and product line, which is why this calculator asks for the roll length printed on what you actually bought rather than assuming one.

It's optional, not required: mulch alone suppresses many weeds on its own, and fabric under organic mulch can interfere with the mulch breaking down into the soil over time. Where fabric earns its keep is under gravel, rock or a hardscape base, where you don't want organic matter building up in the aggregate. If you do mulch on top, use the Mulch Calculator alongside this one for that layer's depth.

Only with caution, and mainly for pathways or in-row weed control rather than under everything: it can restrict water infiltration and make it harder to amend soil or move plants season to season. University extension guidance treats it as one tool among several for weed control rather than a universal default, so weigh it against mulch or manual weeding for actively planted beds.

Switch to "Know the area" above and enter your bed's total square footage directly, measured however you already have it: by adding up simpler shapes, from a site plan, or from a rough on-the-ground estimate. The roll and overlap math runs the same either way.

This calculator doesn't estimate lifespan: it varies widely by fabric weight, UV exposure and what's on top of it. Woven, UV-stabilized commercial-grade fabric under gravel or rock typically outlasts a lighter, unwoven fabric left exposed under mulch, but there's no single authoritative figure to cite here the way there is for overlap or pin spacing.

Landscape fabric is sold and measured by the roll, so this tool solves a coverage-per-roll problem with a seam overlap and pin count, not an area-times-depth volume the way Mulch, Gravel or Soil are. Use those calculators for the material that goes on top of, or instead of, the fabric.