One cubic yard contains 27 cubic feet. With 2-cubic-foot bags of mulch, that is 13.5 bags by volume, so you need 14 whole bags to supply at least one cubic yard. Those 14 bags supply 28 cubic feet, one cubic foot more than a cubic yard. That surplus comes from whole-bag rounding; it is not a separate percentage allowance. The answer changes with the volume printed on the bag.
Use the mulch calculator to work from your bed dimensions, choose a bag size and compare bagged and bulk costs.
Bags of mulch per cubic yard
| Bag size | Equivalent bags | Whole bags to buy |
|---|---|---|
| 1 cubic foot | 27 | 27 |
| 1.5 cubic feet | 18 | 18 |
| 2 cubic feet | 13.5 | 14 |
| 3 cubic feet | 9 | 9 |
| 50 litres | 15.2911 | 16 |
| 100 litres | 7.6455 | 8 |
For litre bags, one cubic yard is approximately 764.555 litres. Divide that volume by the litre capacity. A bag’s weight cannot replace its volume in this calculation: moisture and material density affect weight.
How much area does one bag cover?
Coverage depends on the depth you spread. Convert inches to feet before dividing the bag volume by the layer thickness.
| Depth | Coverage |
|---|---|
| 1 inch | 24 square feet |
| 2 inches | 12 square feet |
| 3 inches | 8 square feet |
| 4 inches | 6 square feet |
These depths illustrate the arithmetic. Choose an appropriate depth for your plants, material and existing mulch; the table is not a planting recommendation. When topping up, calculate only the additional layer you intend to add.
Example: a 12 ft by 8 ft bed
At an added depth of 3 inches, a rectangular bed needs 12 × 8 × 3 ÷ 12 = 24 cubic feet. That is 24 ÷ 27 = about 0.889 cubic yards, or exactly 12 bags of 2 cubic feet.
If you choose a 10% extra-material allowance, the order volume becomes 24 × 1.10 = 26.4 cubic feet. Divide by 2 to get 13.2 bags, then round up to 14 bags. The allowance is your planning assumption, not an automatic requirement.
Round the total order once
For several beds, add the unrounded volumes before converting to bags. Two sections needing 5.2 bags each require 10.4 bags in total, so an 11-bag order is sufficient by volume. Rounding each section first would give 12 bags.
Compare equivalent quantities when checking prices. Bagged cost uses the whole number of bags. A bulk supplier may have a minimum order, delivery charge or fixed delivery increment. Keep those charges separate from the material price.
If you only need a volume, use the cubic yard calculator. For stone, use the gravel calculator and a supplier-provided bulk density.
Reference and method
Unit conversions follow NIST’s conversion factors. The tables and examples are calculated from volume divided by bag capacity. Report a calculation issue.