This mulch calculator tells you how much mulch your beds need — in cubic yards for bulk delivery and in standard bags for store runs — from the area and the depth you want.
Bulk vs bags: one cubic yard covers about 108 sq ft at 3″ deep and equals 13.5 two-cubic-foot bags — beyond roughly 40–50 bags, bulk delivery usually wins on price and effort.
How Much Mulch Do You Need?
Volume = area × depth, with everything in feet. The two delivery formats then fall out: cubic yards (÷ 27) for bulk loads and bags (÷ bag size) for store-bought. Measure your beds’ area with the Square Footage Calculator if you have not already; odd-shaped beds decompose into rectangles and circles. This calculator is part of our Construction Calculators collection.
Worked Example (Verified)
Beds totaling 200 sq ft at the standard 3-inch depth:
- Volume: 200 × 0.25 ft = 50 cubic feet
- Bulk: 50 ÷ 27 = 1.85 cubic yards (order 2)
- Bags: 50 ÷ 2 = 25 bags of the standard 2 cu ft size
Depth Guidance (Where Gardeners Disagree)
- 2 inches: a refresh layer over existing mulch — enough for looks and moisture, light on weed suppression.
- 3 inches: the standard for new beds — the depth most extension services recommend for the moisture + weed balance.
- 4 inches: maximum weed suppression for coarse mulches; keep it pulled a few inches back from trunks and stems (“mulch volcanoes” rot bark and invite pests).
- Fine mulches settle and compact — if anything, order at the top of the range; leftover mulch keeps, a mid-job store run does not feel efficient.
Coverage Rules of Thumb
| Material | Coverage |
|---|---|
| 1 cubic yard | 324 sq ft at 1″ · 162 at 2″ · 108 at 3″ · 81 at 4″ |
| 1 bag (2 cu ft) | 24 sq ft at 1″ · 12 at 2″ · 8 at 3″ · 6 at 4″ |
| 1 cubic yard in bags | 13.5 × 2 cu ft bags |
Related Tools
- Square Footage Calculator — bed areas first
- Construction Calculators — the full collection
Frequently Asked Questions
How many bags of mulch do I need?
Compute cubic feet (area × depth in feet), then divide by the bag size. 200 sq ft at 3″ deep = 50 ft³ = 25 standard 2 cu ft bags.
How many bags equal a cubic yard?
13.5 bags of 2 cu ft (27 ÷ 2). If your project needs more than ~3 cubic yards, bulk delivery is usually cheaper than ~40 bags.
How deep should mulch be?
Three inches is the standard recommendation for new beds; two for a refresh; four for coarse mulch where weeds are the priority. Keep mulch off trunks and stems.
How much does a cubic yard of mulch cover?
108 sq ft at 3 inches deep (162 at 2″, 81 at 4″).
Should I remove old mulch first?
Usually no — top up to the target depth, since old mulch decomposes into the soil. Remove only if it is matted, sour-smelling, or diseased.
Is this mulch calculator free?
Yes — free, instant, no sign-up. The same math prices gravel and soil by volume — see the collection for those.