Landscape Fabric Calculator
To cover a 20 × 30 ft garden bed (600 sq ft) with landscape fabric you need about 660 sq ft after the mandatory 10% seam-overlap allowance — 5 rolls of standard 3 × 50 ft (150 sq ft) fabric.
Reviewed by The ponderloop teamUpdated 2026-07-15How we calculate
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How this number is calculated
0 sq ft (no waste added) ÷ 150 sq ft per roll = 0 rolls
Shopping list
- Heavy-duty woven landscape fabric (3 x 50 ft roll)
- Landscape fabric anchor pins
- Utility knife
- Garden gloves
- Wheelbarrow
- Garden rake
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Methodology & assumptions
We compute the covered area as length × width in feet, subtract any paths or existing plants you enter, then add your chosen overlap waste (10% minimum for a single-seam bed, 15% for a curvy bed with many seams) — unlike other materials, this floor is not optional, since seams must overlap by at least 6 inches or weeds root straight through the gap. The result is divided by the roll coverage (150 sq ft for a standard 3 x 50 ft roll) and rounded up to the next whole roll.
- Clemson Cooperative Extension, Home & Garden Information Center — landscape fabric and weed-barrier guidance
- University of Maryland Extension — mulching and weed-suppression fabric in planted beds
- Manufacturer roll specifications (standard woven landscape fabric, 3 x 50 ft = 150 sq ft)
Worked examples
| Room | Result |
|---|---|
| 20 × 30 ft garden bed, standard overlap | 600 sq ft + 10% waste ≈ 660 sq ft → 5 rolls |
| 10 × 15 ft flower bed, standard overlap | 150 sq ft + 10% waste ≈ 165 sq ft → 2 rolls |
| 40 × 50 ft yard, curvy bed / many seams | 2,000 sq ft + 15% waste = 2,300 sq ft → 16 rolls |
Frequently asked questions
- How much landscape fabric do I need?
- Multiply the bed or yard length by width in feet to get the square footage, subtract any area you are not covering, then add at least 10% for the mandatory seam overlap. Divide by the coverage per roll (150 sq ft for a standard 3 x 50 ft roll) and round up to the next whole roll.
- Does landscape fabric actually work?
- It depends what goes on top. Under gravel or rock, landscape fabric works well for years, since there is no organic material breaking down on top of it for weed seeds to root into. Under mulch, it works for a season or two at best — mulch decomposes into a thin layer of soil on top of the fabric, weeds seed into that layer and root through the fabric weave or its seams, and the fabric itself blocks earthworms and organic matter from mixing into the soil below. Many extension services now recommend a thick mulch layer alone over mulch-plus-fabric for planted beds.
- Landscape fabric vs cardboard — which is better for weed control?
- Cardboard is cheaper, fully biodegradable, and breaks down into the soil within a season or two, which is ideal for one-time bed prep (sheet mulching) but means it needs replacing for ongoing control. Woven landscape fabric lasts years and is the better choice under permanent gravel or rock paths; it is the worse choice under mulch in planted beds, where its long life becomes a liability once roots and weeds start growing on top of and through it.
- Which side of landscape fabric faces up?
- On woven fabric, the smoother, tighter-woven side faces up and the rougher, more textured side faces down against the soil; check the roll for a printed side, which almost always goes up. On non-woven (felt-like) fabric there is no right side. Laying it upside down does not stop weeds, but it does make the fabric wear out and fray faster.
- Do I need to pin down landscape fabric, and how?
- Yes. Use 6-inch landscape fabric anchor pins (sometimes called staples) spaced every 3-4 feet along the edges and every seam, plus extra pins at the overlaps themselves so wind, foot traffic, or rain does not pull the seams apart and open a gap for weeds.