One 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
The coverage depends on how thick you spread it. A cubic yard is the standard unit mulch is sold in — that's a pile 3 feet wide, 3 feet long, and 3 feet tall. How far that pile stretches across your garden bed depends entirely on the depth you choose.
Most landscapers recommend 2 to 3 inches of mulch for weed suppression and moisture retention. At 2 inches, one yard covers roughly 162 square feet. At 3 inches, it covers about 108 square feet. If you spread it thinner — say 1 inch — one yard will stretch to 324 square feet, but it won't suppress weeds as effectively and will break down faster.
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.
- A 2- to 3-inch depth is standard for weed control and moisture retention in most garden beds.
- Thinner mulch (1 inch) covers more ground but breaks down faster and provides less weed suppression.
- Measure your bed in square feet, decide your target depth, and divide the square footage by the coverage rate to find how many yards you need.
How to calculate coverage for your garden bed
Start by measuring the length and width of your bed in feet, then multiply them together to get square footage. A bed that is 10 feet long and 4 feet wide is 40 square feet. A circular bed with a 6-foot diameter is roughly 28 square feet.
Once you know the square footage, decide what depth you want. Then divide your square footage by the coverage rate for that depth. If your bed is 100 square feet and you want 2-inch mulch, divide 100 by 162. You need roughly 0.6 cubic yards — so order 1 yard to have extra on hand.
If you have multiple beds, add all the square footages together before calculating. A 40-square-foot bed plus a 60-square-foot bed equals 100 square feet total, and you can order for the whole project at once.
Why depth matters more than you might think
Mulch breaks down over time as it decomposes and gets worked into the soil by worms and microbes. A 1-inch layer may look thin but will compress further as it settles. By midsummer, it can be half that thickness, leaving weeds room to push through.
A 2-inch layer gives you a safety margin. It suppresses most weeds, retains soil moisture longer during dry spells, and keeps soil temperature more stable. By late summer, it will have settled to roughly 1.5 inches — still effective.
Three inches is overkill for most beds but makes sense if you are dealing with aggressive perennial weeds or if you live in a very hot, dry climate. It also looks fuller visually, which some gardeners prefer. The trade-off is that you will need more mulch and it will take longer to break down, which can sometimes trap moisture against plant stems and cause rot.
Common mistakes that waste mulch
The biggest mistake is piling mulch against tree trunks and plant stems. This creates a "mulch volcano" that traps moisture and can cause rot and pest damage. Keep mulch 3 to 4 inches away from any stem or trunk, even if it leaves a small gap.
Another common error is spreading mulch too thin to save money. A 0.5-inch layer looks like you tried but won't suppress weeds or retain moisture. You will end up buying more mulch sooner to top it off, which costs more in the long run.
Spreading mulch unevenly is also wasteful. Some spots end up 4 inches deep while others are barely 1 inch. Use a landscape rake to level it as you go, aiming for consistent depth across the whole bed.
Mulch types and whether they affect coverage
Coverage rates are the same whether you use shredded hardwood, pine bark, cedar, or compost-based mulch — one cubic yard is still one cubic yard. The difference is in how fast it breaks down and what it costs.
Hardwood mulch lasts longer and breaks down slowly, so you may not need to top it off for two years. Pine bark breaks down faster, usually needing a refresh every 12 to 18 months. Cedar and cypress smell better and resist insects, but cost more. Compost-based mulch enriches soil as it breaks down but may need topping off annually.
The type you choose affects your budget over time, but not how much ground one yard will cover at a given depth.
How to order the right amount and avoid shortages
Calculate your square footage, pick your depth, and order slightly more than your math suggests. If your calculation says you need 2.3 yards, order 3. Mulch settles during delivery, and you will almost certainly have a small area you missed or a spot that needs extra depth.
Mulch is usually sold by the cubic yard at landscape supply yards, garden centers, and some big-box stores. Prices vary widely by location and type — anywhere from $25 to $60 per yard depending on what you choose and where you live. Delivery fees explore if you order less than a certain amount, often 5 yards or more, so factor that into your decision.
If you are ordering a small amount — say 1 or 2 yards — it may be cheaper to pick it up yourself than to pay a delivery fee. Call ahead to confirm the yard has mulch in stock and ask about their bagging options if you do not have a truck.
Frequently Asked Questions
What if I want to go deeper than 3 inches?
You can, but it is rarely necessary. Depths beyond 3 inches can trap moisture against plant stems and slow decomposition. If you have a specific reason — severe weed pressure or extreme heat — go ahead, but measure carefully so you do not waste mulch.
Does wet mulch cover less ground than dry mulch?
Wet mulch is heavier but takes up the same volume. One cubic yard is one cubic yard whether it rained yesterday or not. However, wet mulch is harder to spread evenly, so you may end up with thicker spots and thinner spots. Spread it on a dry day if you can.
Can I mix mulch types to stretch my budget?
Yes. You can blend a more expensive mulch like cedar with a cheaper hardwood mulch and still get the same coverage. Mix them as you spread or layer them — cedar on top for appearance and smell, hardwood underneath for bulk and longevity.
How do I know if I need to add more mulch next year?
Check the depth in late spring or early summer. If it has settled to 1 inch or less, add a 1-inch top layer. You do not need to remove the old mulch — just rake it level and add fresh material on top. This is much cheaper than replacing it all.
What if my bed is an odd shape?
Break it into rectangles and triangles, calculate each section separately, then add them together. A bed shaped like an L is really two rectangles. A triangular corner is half the base times the height. This method works for any irregular shape.