One cubic yard of mulch covers 324 square feet at 1 inch deep
A cubic yard is a volume measurement—3 feet long, 3 feet wide, and 3 feet tall. When you spread that volume across your garden bed, how much ground it covers depends entirely on how thick you lay it. At the standard mulch depth of 1 inch, one cubic yard covers 324 square feet. At 2 inches deep, the same yard covers 162 square feet. At 3 inches deep, it covers 108 square feet.
Most landscapers recommend 2 to 3 inches of mulch for weed suppression and moisture retention. That means a single cubic yard will cover between 108 and 162 square feet of garden bed. If you're buying mulch by the bag instead of by the yard, each 2-cubic-foot bag covers about 8 square feet at 3 inches deep, or 12 square feet at 2 inches deep.
Key Takeaways
- One cubic yard of mulch covers 324 square feet at 1 inch deep, 162 square feet at 2 inches deep, and 108 square feet at 3 inches deep.
- Most garden beds need 2 to 3 inches of mulch to suppress weeds and hold moisture, so plan for 108 to 162 square feet per cubic yard.
- Bagged mulch is sold by the cubic foot, not the yard—a 2-cubic-foot bag covers roughly 8 to 12 square feet depending on depth.
- Measure your bed length and width in feet, multiply them together, then divide by the coverage rate for your chosen depth.
How to calculate mulch needed for your bed
Start by measuring the length and width of your garden bed in feet. Multiply those two numbers to get the total square footage. Then use the coverage rates above to find how many cubic yards you need.
For example: a bed that is 10 feet long and 8 feet wide is 80 square feet. If you want 2 inches of mulch, divide 80 by 162 (the coverage at 2 inches). You need about 0.5 cubic yards, or half a yard. If you want 3 inches, divide 80 by 108. You need about 0.75 cubic yards.
Most mulch suppliers will sell you half-yard and quarter-yard amounts, though delivery fees may explore to small orders. Buying a full yard and using the extra on other beds is often cheaper than paying a delivery charge for a half yard.
Why depth matters more than you think
The difference between 1 inch and 3 inches is not just appearance—it changes how well mulch does its job. At 1 inch deep, mulch is thin enough that weeds can push through, and it dries out faster in sun. At 2 inches, you get solid weed suppression and decent moisture retention. At 3 inches, you get maximum weed blocking and the longest time between waterings, but you also risk smothering shallow-rooted plants if the mulch piles against their stems.
Never pile mulch directly against tree trunks or plant stems. Leave a 2- to 3-inch gap around each plant so air can reach the base. This prevents rot and pest damage. The mulch ring should look like a donut, not a volcano.
Mulch coverage by depth—quick reference table
| Depth | Square feet per cubic yard | Cubic yards needed for 100 sq ft |
|---|---|---|
| 1 inch | 324 sq ft | 0.31 yards |
| 2 inches | 162 sq ft | 0.62 yards |
| 3 inches | 108 sq ft | 0.93 yards |
| 4 inches | 81 sq ft | 1.23 yards |
Bagged mulch versus bulk mulch
Bagged mulch is convenient for small beds and lets you choose the exact type—cedar, hardwood, pine, or dyed. A standard 2-cubic-foot bag costs between $3 and $8 depending on the type and your location. You'll need 13 to 14 bags to equal one cubic yard. For a 100-square-foot bed at 2 inches deep, you'd need about 8 bags.
Bulk mulch from a landscape supplier is cheaper per cubic yard—usually $25 to $50 per yard depending on type and region—but requires either a truck to haul it or a delivery fee. Delivery typically costs $50 to $100. Bulk makes sense if you're covering more than 300 square feet or if you're doing multiple beds at once.
Bagged mulch also settles and compacts over time, so you may need to add more after a few months. Bulk mulch settles faster in the first few weeks, then stabilizes.
Common mistakes when estimating mulch
The biggest mistake is underestimating depth. Many people think 1 inch will be enough and end up with thin coverage that doesn't suppress weeds. Buy for 2 inches minimum unless you're just refreshing an existing bed that already has mulch underneath.
The second mistake is forgetting to account for settling. Mulch compacts as it absorbs water and breaks down. Plan to add a top-up layer every spring, especially if you used bulk mulch. A 3-inch layer will compress to about 2 inches by midsummer.
A third mistake is piling mulch against plant stems and tree trunks. This traps moisture and invites insects and disease. Always leave a clear ring around the base of each plant.
Frequently Asked Questions
How do I measure an irregularly shaped bed?
Divide the bed into rectangles, measure each one separately, add the square footages together, then calculate mulch needed for the total. For curved beds, estimate by breaking them into rough sections. Overestimate slightly rather than underestimate—leftover mulch can go on other beds or be stored for next year.
Does mulch type affect how much I need?
No. Cedar, hardwood, pine, and dyed mulch all have the same volume, so one cubic yard covers the same square footage regardless of type. The difference is in cost, appearance, and how long the mulch lasts before breaking down. Cedar lasts longest but costs more; hardwood is the middle ground; dyed mulch is cheaper but may fade.
Can I use less mulch if I put down landscape fabric first?
Landscape fabric blocks weeds, but it doesn't replace mulch's role in retaining moisture and regulating soil temperature. You can use 1 inch of mulch over fabric instead of 2 to 3 inches, but you'll still need enough to cover the fabric completely. Many gardeners skip fabric and use 3 inches of mulch instead—it's simpler and works just as well.
What if I have a very large area to cover?
For areas over 500 square feet, bulk mulch is almost always cheaper than bags, even with delivery. Call local landscape suppliers and ask for a quote on the cubic yardage you need. Most will deliver within a few days. Have a plan for where the pile will sit—mulch trucks need a flat, accessible spot.
How often do I need to add more mulch?
Mulch breaks down slowly over time. Add a 1-inch refresh layer every spring, or every other spring if you used 3 inches initially. In hot, dry climates, mulch breaks down faster and may need refreshing annually. In cooler, wetter climates, it lasts longer.