Mulch is sold by the cubic yard, but you measure your beds in square feet, so the question is always how to connect the two. Here is the short answer: one cubic yard of bark mulch covers about 100 square feet at 3 inches deep. Go shallower and it stretches further, go deeper and you need more. This guide gives you the formula, a coverage table, and how deep to spread it.
The quick formula
- Measure the length and width of your bed in feet and multiply for square feet.
- Pick a depth in inches and divide by 12 to get feet.
- Multiply square feet by that depth to get cubic feet.
- Divide cubic feet by 27 to get cubic yards.
Example: a 400 square foot bed at 3 inches deep is 400 multiplied by 0.25, which is 100 cubic feet, or about 3.7 cubic yards. Round up a little so you are not short.
Coverage at a glance
One cubic yard equals 27 cubic feet. Here is what a yard of mulch covers at common depths:
| Depth | Coverage per cubic yard |
|---|---|
| 1 inch | ~324 sq ft |
| 2 inches | ~162 sq ft |
| 3 inches | ~108 sq ft |
| 4 inches | ~81 sq ft |
Most beds do best with 2 to 3 inches of mulch, so a cubic yard covering roughly 100 to 160 square feet is a good planning number.
How deep should bark mulch be?
- Maintaining an existing bed: 1 to 2 inches to refresh the look and keep coverage.
- New beds and weed suppression: 3 inches, which blocks most light to weed seeds.
- Around trees and shrubs: 2 to 3 inches, kept a few inches back from trunks and stems.
Avoid piling mulch against trunks. A volcano of mulch traps moisture against the bark and invites rot. Keep a small gap around the base.
Why mulch is worth it
A few inches of bark mulch does real work in a bed. It holds soil moisture so you water less, blocks light to keep weeds down, moderates soil temperature through hot and cold spells, and breaks down over time to feed the soil. It also gives beds a clean, finished edge that ties a landscape together.
How often to replace it
Bark mulch breaks down gradually, so plan to top it off about once a year to keep your depth and color. You usually do not need to remove the old layer. Just rake it to loosen any matting and add fresh mulch on top to your target depth.
Frequently asked questions
How much does a yard of mulch cover?
About 100 square feet at 3 inches deep, or roughly 160 square feet at 2 inches. One cubic yard is 27 cubic feet, so coverage scales with how deep you spread it.
How many bags of mulch are in a cubic yard?
Bagged mulch is often sold in 2 cubic foot bags, so a cubic yard is about 13 to 14 bags. For larger beds, buying bulk by the yard is usually more economical.
How deep should I spread bark mulch?
Two to three inches is ideal for most beds. Three inches helps suppress weeds in new beds, while 1 to 2 inches refreshes an existing layer. Keep mulch a few inches off trunks and stems.
How often should I add new mulch?
About once a year. Bark mulch breaks down over time, so topping it off annually maintains your depth, color, and weed suppression. Rake the old layer first, then add fresh on top.
Order your mulch
Figure your beds with the coverage calculator, then browse our bark mulch and topsoil. We deliver nationwide from our California yards, by the bag or by the truckload.