Material takeoff
How much landscape fabric do I need?
Set your roll width and seam overlap. Overlap eats more coverage than people expect, especially on narrow rolls.
How the math works
effective width = roll width − overlap
linear feet needed = area × (1 + waste) ÷ effective width
rolls = linear feet ÷ roll length, rounded up.
A four foot roll with six inches of overlap gives you three and a half feet of coverage per pass. Wider rolls waste proportionally less on seams, so on a large area a twelve foot roll is meaningfully more efficient than three four foot rolls.
The estimate is approximate by nature. Irregular shapes waste more than any formula predicts.
When fabric helps and when it does not
Under gravel and stone, fabric earns its keep. It keeps stone from working down into soil and soil from pumping up into stone, which is what makes a gravel path disappear over five years.
Under organic mulch it is more debatable. The mulch decomposes into a soil layer on top of the fabric, weeds germinate in that layer, and their roots grow through the mesh — so you get the weeds anyway plus a fabric layer that makes planting and amending harder. Many landscapers skip it in planting beds.
Under a paver base, use a separation geotextile rather than the light woven fabric sold for beds. They are different products with different strengths.
Whatever you use, pin it. Fabric that lifts at the edges is worse than no fabric.
Where people get it wrong
- No overlap allowance
- Seams need six inches or so. On narrow rolls that is a substantial share of the coverage.
- Bed fabric under pavers
- Paver base needs a heavier separation geotextile, not lightweight bed fabric.
- Fabric in planting beds by default
- It complicates planting and amending, and does not stop weeds seeding into the mulch above it.
- Skipping the pins
- Unpinned fabric migrates and lifts. Pins are cheap.
Background
Fabric is sold in rolls, and the number of rolls depends on more than area. Every seam overlaps, and on a three foot roll a six inch overlap consumes a sixth of your coverage before you cut anything.
What you need for the job
Common questions
How much landscape fabric do I need?
Divide your area by the roll width minus overlap to get linear feet, then divide by roll length. The calculator above handles it.
How much should landscape fabric overlap?
Six inches is the common recommendation for seams, and more at edges you plan to bury.
Does landscape fabric stop weeds?
It blocks weeds coming from below for a few years. It does not stop seeds landing in the mulch on top, which is where most bed weeds actually come from.
Should I put landscape fabric under gravel?
Generally yes. It stops the stone from working into the soil, which is the main way gravel areas fail.
How long does landscape fabric last?
Woven fabric under stone can last a decade or more. Lighter spun fabric in beds often degrades within a few years, especially where sunlight reaches it.
Measuring by hand is where estimates go wrong
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