The math behind your estimate
The inputs, allowance, and rounding stay visible.
- Volume
- Volume = Length × Width × Depth, summed over all beds
- Bags
- Bags = Volume × (1 + allowance %) ÷ bag volume, rounded up
Assumptions
- Bag volumes are as labeled (2 ft³ is the most common US size). One cubic yard equals 13.5 × 2 ft³ bags.
- Coverage assumes an even layer at your chosen depth over cleared beds. Mulch settles roughly 25% over a season, which the allowance partly offsets.
Frequently asked questions
- How deep should mulch be?
- 2–3 inches for most beds: enough to suppress weeds and hold moisture, but not so deep that it suffocates roots. Keep mulch a couple of inches clear of trunks and stems, and go to 3–4 inches only for coarse chips in open areas.
- How many bags of mulch are in a cubic yard?
- 13.5 bags at the common 2 ft³ size (27 ÷ 2). If you need more than about 1–2 yards, bulk delivery is usually cheaper per yard than bags — compare your local prices at that break point.
- How much does a 2 cubic foot bag of mulch cover?
- At 3 inches deep, one 2 ft³ bag covers 8 square feet; at 2 inches, 12 square feet. Halve or scale accordingly — depth is the biggest lever on how far your mulch goes.
- Should I buy extra mulch?
- A 5% allowance covers uneven spreading and slight settling on fresh beds. If you're topping up next season anyway, leftover bags store fine — running short mid-bed is the annoying outcome.
Sources
- Standard US mulch bag sizes (1.5, 2, 3 ft³) and yard/bag equivalence