A yard of mulch covers 324 square feet at 1 inch deep
One cubic yard of mulch — the standard unit sold at garden centers — covers 324 square feet when spread 1 inch thick. That number comes from the math: a cubic yard is 27 cubic feet, and 27 cubic feet spread across 1 inch of depth equals 324 square feet. The depth you choose changes the coverage dramatically, so knowing your target depth before you buy is the only way to order the right amount.
Most landscaping jobs use mulch between 2 and 4 inches deep. At 2 inches, one yard covers 162 square feet. At 3 inches, it covers 108 square feet. At 4 inches, it covers 81 square feet. Deeper mulch suppresses weeds better and retains moisture longer, but it also costs more and can pile up against tree trunks if you're not careful about placement.
Key Takeaways
- One cubic yard of mulch covers 324 square feet at 1 inch deep, 162 square feet at 2 inches, and 108 square feet at 3 inches.
- Most garden beds use 2 to 3 inches of mulch, which means a single yard covers between 108 and 162 square feet in a typical installation.
- Mulch settles and decomposes over time, so the depth you lay down will be thinner after a few months.
- Ordering by square footage and depth is more accurate than guessing how many yards you need.
How to calculate mulch coverage for your space
Measure the length and width of each bed in feet, then multiply them together to get square footage. If your bed is 10 feet long and 4 feet wide, that's 40 square feet. Add up all your beds to get your total square footage.
Once you know your total square footage and the depth you want, use this table to find how many yards you need:
| Depth | Coverage per yard | Yards needed for 100 sq ft | Yards needed for 500 sq ft |
|---|---|---|---|
| 1 inch | 324 sq ft | 0.3 yards | 1.5 yards |
| 2 inches | 162 sq ft | 0.6 yards | 3.1 yards |
| 3 inches | 108 sq ft | 0.9 yards | 4.6 yards |
| 4 inches | 81 sq ft | 1.2 yards | 6.2 yards |
For irregular shapes, break the bed into rectangles, calculate each one separately, and add them together. A bed shaped like an L is just two rectangles. A circular bed needs the radius (half the width), then use the formula 3.14 × radius × radius to find square footage.
Why depth matters more than you think
The difference between 2 and 3 inches of mulch is not small. At 2 inches, you suppress most annual weeds but not perennial ones with deep roots. At 3 inches, you stop most weeds from germinating at all. The trade-off is cost: 3 inches requires 50 percent more mulch than 2 inches for the same space.
Mulch also settles as it dries and decomposes. Fresh mulch laid at 3 inches will be closer to 2 inches after a month or two, especially if you water the beds regularly. Some gardeners add a half-inch extra to account for settling, or they top off beds in late spring after the initial settling is done.
Keep mulch 6 inches away from tree trunks and the base of shrubs. Mulch piled against wood promotes rot and creates a highway for insects and rodents to reach the bark. Measure your bed width from the edge of the trunk outward, not from the edge of the bed inward.
Common mulch types and their coverage
All mulch is sold by the cubic yard, so the coverage math is the same whether you buy shredded hardwood, pine bark, cedar, or wood chips. The difference is in how fast it breaks down and how long it lasts. Hardwood mulch lasts 2 to 3 years. Pine bark lasts 1 to 2 years. Cedar lasts longer but costs more.
Dyed mulch and natural mulch cover the same square footage per yard. The dye does not add volume or change how it spreads. The main difference is appearance: dyed mulch stays dark longer, while natural mulch fades to gray as it weathers.
Rubber mulch and playground chips are also sold by the cubic yard, but they do not break down like wood mulch. They last 8 to 10 years, so you order them the same way but replace them less often. The coverage per yard is the same.
Ordering mulch in bulk versus bags
Bulk mulch is cheaper per cubic yard than bagged mulch, but you need a place to store it and a way to spread it. A cubic yard of bulk mulch weighs 400 to 600 pounds depending on moisture content. Most landscape suppliers deliver bulk mulch for a fee, usually between $40 and $100 per delivery.
Bagged mulch costs more per yard but comes in 2-cubic-foot bags that are easier to handle and store. A single cubic yard requires 13 to 14 bags. Bagged mulch is useful for small beds or when you want to add mulch to existing beds without ordering a full yard.
If you order bulk mulch, ask the supplier whether the price is for loose mulch or compressed mulch. Loose mulch takes up more space in the truck but settles to a smaller volume once it's in your bed. Compressed mulch is denser and covers less area per yard.
How to avoid ordering too much or too little
Round up your square footage slightly. If your beds total 247 square feet and you want 3 inches of depth, you need 2.3 yards. Order 2.5 yards instead of 2 yards. The extra mulch can go in low spots or be saved for spring top-offs. Running short means a second delivery fee.
Account for obstacles. Mulch spreads around rocks, plants, and edging, but it does not cover them. If your 100-square-foot bed has a large boulder taking up 10 square feet, you really need mulch for 90 square feet. Subtract the square footage of anything that will sit on top of the mulch.
Ask the supplier what their minimum order is. Many landscape suppliers have a minimum of 1 yard or 2 yards for delivery. If your beds only need 0.5 yards, you may have to buy a full yard and use the rest elsewhere or save it for later.
Frequently Asked Questions
How deep should mulch be in a vegetable garden?
Vegetable beds typically use 2 to 3 inches of mulch. Deeper mulch keeps soil cooler and moister, which helps during hot summers, but it can also slow soil warming in spring. Many gardeners use 2 inches early in the season and add another inch in mid-summer.
Does mulch settle, and do I need to add more each year?
Yes, mulch settles within the first few weeks and continues to decompose over months. After a year, you may lose 1 to 2 inches of depth depending on the type and climate. Many gardeners add a 1-inch top-off each spring to maintain depth and suppress new weeds.
Can I mix different types of mulch in the same bed?
Yes. Mixing types does not affect coverage or performance. Some gardeners use cheaper wood chips as a base layer and a more attractive mulch like cedar on top. Calculate coverage for the total depth you want, regardless of how many types you use.
What if my bed is oddly shaped or has curves?
Measure the longest length and widest width, multiply them, then subtract about 20 percent for the curved or irregular parts. For a bed that is roughly 10 feet long and 6 feet wide but with curved edges, calculate 60 square feet and subtract 12 square feet, giving you 48 square feet to work with.