A yard of mulch covers 324 square feet at 1 inch deep
One cubic yard of mulch — the standard unit sold at garden centers — spreads across 324 square feet when laid 1 inch thick. That number changes with depth. At 2 inches deep, the same yard covers 162 square feet. At 3 inches deep, it covers 108 square feet. The math is straightforward: a cubic yard contains 27 cubic feet, so divide 27 by your desired depth in feet to get square footage.
Most landscapers and homeowners explore mulch between 2 and 4 inches deep. Two inches is the minimum for weed suppression and moisture retention. Three inches is the standard for flower beds and around trees. Four inches or deeper can trap moisture against plant stems and create conditions for rot, so avoid piling it higher than that.
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 landscaping jobs use 2 to 3 inches of depth, which means one yard covers between 108 and 162 square feet in practice.
- To calculate how many yards you need, measure your bed in square feet, decide your depth, and divide the square footage by the coverage at that depth.
- Mulch settles and breaks down over time, so ordering 10 to 15 percent extra accounts for settling in the first few weeks.
How to calculate mulch needed for your space
Start by measuring the length and width of each bed in feet, then multiply to get square footage. If your bed is irregular, break it into rectangles, calculate each one, and add them together. A bed that is 10 feet long and 4 feet wide is 40 square feet.
Next, decide your depth. For new beds or heavy weed pressure, use 3 inches. For maintenance around established plants, 2 inches usually works. Convert your depth to feet by dividing by 12 — so 3 inches becomes 0.25 feet. Divide your square footage by the coverage rate at that depth. A 40-square-foot bed at 3 inches deep needs 40 ÷ 108 = 0.37 cubic yards, which rounds to half a yard.
If you have multiple beds, add all the square footage together before calculating. A 100-square-foot total at 2 inches deep needs 100 ÷ 162 = 0.62 cubic yards, or roughly two-thirds of a yard. Most suppliers sell in whole or half-yard increments, so round up.
Why depth matters for mulch performance
Mulch works by blocking sunlight from reaching weed seeds and by slowing water evaporation from the soil. At 1 inch deep, it does neither job well — weeds still push through and soil dries faster. At 2 inches, you get basic weed suppression and some moisture benefit. At 3 inches, both effects are strong enough for most residential beds.
Going deeper than 3 or 4 inches creates problems. Mulch that piles against tree trunks or plant stems traps moisture and can cause rot, fungal disease, or bark damage. Thick mulch also stays wet longer after rain, which can encourage fungal growth in humid climates. The sweet spot for most situations is 2 to 3 inches — thick enough to work, shallow enough to stay safe.
Mulch settling and ordering extra
Fresh mulch settles as it dries and as the pieces break down. You may lose 10 to 15 percent of your depth in the first few weeks. If you need your bed to stay at 3 inches, order enough mulch for 3.5 inches to account for settling. This is especially true for wood chips, which settle more than shredded bark.
Mulch also breaks down over time — wood chips typically last 1 to 2 years before they begin to decompose into the soil. Shredded hardwood bark lasts slightly longer. Plan to refresh your beds every 1 to 2 years, adding a fresh 1 to 2 inches on top of what remains. You do not need to remove old mulch unless it has become matted or compacted.
Coverage chart for common bed sizes
| Bed Size (sq ft) | Yards at 1 inch | Yards at 2 inches | Yards at 3 inches |
|---|---|---|---|
| 50 | 0.15 | 0.31 | 0.46 |
| 100 | 0.31 | 0.62 | 0.93 |
| 150 | 0.46 | 0.93 | 1.39 |
| 200 | 0.62 | 1.23 | 1.85 |
| 300 | 0.93 | 1.85 | 2.78 |
Use this table as a quick reference for common bed sizes. Round up to the nearest half-yard when ordering, since suppliers do not sell quarter-yard amounts at most locations. If your bed falls between two sizes, calculate the difference and add it to the smaller amount.
The table assumes you are ordering whole or half yards and rounding up. For example, a 150-square-foot bed at 2 inches needs 0.93 yards, which you would order as 1 full yard. This gives you a small buffer for settling and ensures complete coverage.
Frequently Asked Questions
How much does a cubic yard of mulch weigh?
A cubic yard of mulch typically weighs between 400 and 800 pounds, depending on the type and moisture content. Shredded hardwood bark is heavier than wood chips. Freshly delivered mulch is wetter and heavier than mulch that has dried for a few days. If you are having it delivered, ask the supplier for the weight so you know what to expect.
Can I use less mulch if I lay down landscape fabric first?
Landscape fabric blocks weeds from below, but mulch still needs to be thick enough to block light from above. You can reduce depth slightly — from 3 inches to 2.5 inches — but do not go below 2 inches even with fabric. The fabric also tears over time and can become visible, so you still need enough mulch to cover it completely.
What if my bed is oddly shaped?
Break the bed into straightforward shapes — rectangles and triangles. Measure each one, calculate the area, and add them together. For a triangle, multiply base times height and divide by 2. For a circle, multiply the radius by itself, then multiply by 3.14. Once you have the total square footage, use the depth formula to find how many yards you need.
Should I remove old mulch before adding new mulch?
You do not need to remove old mulch unless it is matted, compacted, or moldy. If it still looks loose and natural, rake it out lightly and add 1 to 2 inches of fresh mulch on top. This saves money and effort. Only remove it if it has become a solid layer that water cannot penetrate.
Does mulch type affect how much I need?
No. Coverage is based on volume, not type. One cubic yard of wood chips covers the same square footage as one cubic yard of shredded bark or pine straw at the same depth. The type affects how long it lasts, how it looks, and how it breaks down, but not how far it spreads.