Landscape Fabric Calculator
Calculate how many rolls of landscape fabric you need for a weed-barrier layer under mulch or rock, plus total cost.
How this calculator works
Landscape fabric is a woven weed-barrier sheet laid under mulch or rock beds. This calculator divides your bed’s area by the standard 300 square foot roll coverage (a 3 ft × 100 ft roll), then rounds up to a whole roll since partial rolls aren’t sold. Turning on the waste toggle adds 10% to approximate the material consumed by overlapping seams.
Formula: Rolls = Area sq ft ÷ 300 sq ft per roll (rounded up to a whole roll).
Worked example
A 30 ft × 10 ft bed (300 sq ft):
- Rolls needed: 300 ÷ 300 = 1 rolls
- At $40/roll, that’s $40.00 before waste.
Coverage reference
| Area | Rolls needed |
|---|---|
| 15 × 5 ft | 1 rolls |
| 30 × 10 ft | 1 rolls |
| 60 × 20 ft | 4 rolls |
How to measure your beds
Measure the full length and width of each bed you’re lining, including any curves or irregular edges rounded up to the nearest rectangle, since fabric strips need to be cut generously to reach every edge. If your beds are split across the yard, total their combined area and turn on the waste toggle to account for seam overlaps between strips.
Frequently asked questions
What size roll of landscape fabric does this calculator assume?
It assumes a standard 3 ft × 100 ft roll, which covers 300 square feet before overlap. Rolls also come in narrower widths like 4 ft or 6 ft with proportionally different total coverage, so check your specific roll's dimensions if it's not the 3 ft width.
Why do I need to overlap seams by 6 inches?
Weeds are relentless about finding any gap, and a butted seam with no overlap eventually opens as the fabric shifts and settles. Turning on the waste toggle approximates the extra material that 6-inch seam overlaps consume across a bed with multiple fabric strips.
Is landscape fabric better under mulch or under rock?
It holds up much better under rock. Under organic mulch, the mulch itself breaks down into a thin soil layer on top of the fabric within a few years, giving weed seeds a place to root right above the barrier — largely defeating the purpose. Under rock, that organic buildup doesn't happen, so the fabric keeps working for far longer.
Does landscape fabric block water and nutrients from reaching plant roots?
A quality woven, permeable landscape fabric lets water and air pass through while still blocking weed germination, so established plants aren't starved. Solid plastic sheeting is a different product entirely and isn't a substitute — it blocks water and should be avoided under living beds.
How do I secure landscape fabric once it's laid?
Anchor it every few feet with landscape fabric staples (metal garden pins), doubling up along seams and bed edges where wind or foot traffic can lift it. Skipping staples is the most common reason fabric bunches up or shifts out of place within the first season.
Estimates only. Verify quantities with your supplier before purchasing.