Pick your mulch type and the calculator sets a typical depth for it. Enter the size of your beds to get cubic yards and bags.
Extra for settling and cost
Bag sizes vary by brand. Check the volume printed on the bag.
How deep should mulch be?
Most garden beds need 2 to 4 inches of mulch, and 3 inches is a good all-round depth. Less than 2 inches lets weeds through. More than 4 inches can keep the soil too wet and starve roots of air.
Keep mulch a few inches away from tree trunks and plant stems. Mulch piled up against the bark holds moisture there and invites rot and pests.
Types of mulch
| Mulch | Typical depth | Good to know |
|---|---|---|
| Shredded hardwood | 3 in | Knits together, so it stays put on slopes. Breaks down and feeds the soil. |
| Pine bark nuggets | 3 in | Lasts longer than shredded mulch, but light nuggets can float away in heavy rain. |
| Dyed red or black mulch | 3 in | Keeps a strong color for a season or so, then fades. Often made from recycled wood. |
| Wood chips | 3 in | Coarse and cheap, sometimes free from tree services. Good for paths and large areas. |
| Rubber mulch | 2 in | Doesn’t rot, so it rarely needs topping up. Often used in play areas. |
For play areas, check playground safety guidance for the depth of rubber mulch or wood chips under equipment. It’s usually much deeper than in a garden bed.
Worked example
A 200 square foot bed, 3 inches deep:
- 200 × 3 ÷ 12 = 50 cubic feet, or 1.85 cubic yards
- With 10 percent extra for settling: 2.04 cubic yards
- In 2 cubic foot bags: 55 ÷ 2 = 28 bags
How far does mulch go?
| Depth | 1 cubic yard covers | 1 bag (2 cu ft) covers |
|---|---|---|
| 2 in | 162 sq ft | 12 sq ft |
| 3 in | 108 sq ft | 8 sq ft |
| 4 in | 81 sq ft | 6 sq ft |
Bags or bulk?
Most bagged mulch comes in 2 cubic foot bags, so 13.5 bags make one cubic yard. Some brands sell 1.5 or 3 cubic foot bags, so check the label. Bulk mulch is sold by the cubic yard and is usually much cheaper for big jobs.
Refreshing old mulch
You don’t need to start from scratch every year. Rake the old mulch to loosen it, then add enough new mulch to bring the total back to 2 to 4 inches. That’s often only an inch or so. If the old layer has matted into a crust or is already deeper than 4 inches, remove some first.
Frequently asked questions
How much mulch do I need?
Multiply the length and width of each bed in feet, multiply by the depth in inches, then divide by 324 to get cubic yards. The calculator does this for you and adds 10 percent for settling.
How many bags of mulch are in a yard?
13.5 bags of 2 cubic feet, or 9 bags of 3 cubic feet.
How much area does a yard of mulch cover?
About 108 square feet at 3 inches deep, 162 square feet at 2 inches, or 81 square feet at 4 inches.
Should I put landscape fabric under mulch?
It’s optional. Fabric slows weeds but also stops the mulch from breaking down into the soil. In planting beds many gardeners skip it and use a thicker layer of mulch instead.
Is rubber mulch better than wood mulch?
Rubber mulch lasts much longer and doesn’t blow away easily, but it doesn’t improve the soil and gets hot in the sun. Wood mulch needs topping up but feeds the soil as it breaks down.
Results are estimates for planning. Bag sizes vary by brand. See How We Calculate for the formulas and values we use.