Material planning guide
Mulch Coverage by Depth: Cubic Yard and Bag Table
A fixed volume covers less ground as the layer gets deeper. Use coverage tables for quantity planning after choosing a suitable depth for the particular planting and material.
Reviewed September 6, 2026Coverage comes from volume divided by depth
Coverage in square feet equals volume in cubic feet × 12 ÷ depth in inches. The table describes geometry only; it is not a recommendation to use each depth.
Coverage before allowance
| Depth | 1 yd³ covers | 2 ft³ bag covers |
|---|---|---|
| 1 in | 324 ft² | 24 ft² |
| 2 in | 162 ft² | 12 ft² |
| 3 in | 108 ft² | 8 ft² |
| 4 in | 81 ft² | 6 ft² |
Example: topping up an existing bed
Suppose a 12 × 18 ft bed requires an additional 2-inch layer. The added volume is 216 × 2 ÷ 12 = 36 ft³, or 1.333 yd³. Without a purchase allowance, that is eighteen 2 ft³ bags. Do not use the total desired depth if some suitable material is already present.
Keep measurement and horticulture separate
Depth changes both quantity and growing conditions. The right choice depends on plantings, existing material, and the mulch itself. Measure several points where the bed is uneven, then choose an explicit allowance for uncertainty instead of silently increasing all dimensions.
- Exclude surfaces that will remain uncovered.
- Avoid counting existing material as a new purchase.
- Check appropriate depth with planting guidance rather than this conversion table.
Sources and product references
- University of Minnesota Extension — mulching
Organic and inorganic mulch behavior; application depth depends on the landscape.
- NIST — SI units: volume
Unit relationships; supplier product coverage and prices remain separate inputs.