A yard of mulch is 27 cubic feet, which covers roughly 100 to 160 square feet depending on depth

When you order mulch by the yard, you are buying a volume measurement, not a weight or area. One cubic yard equals 27 cubic feet. How much ground that covers depends entirely on how deep you spread it. At 3 inches deep—the standard depth for most landscaping—one yard covers about 100 square feet. At 2 inches deep, it stretches to roughly 160 square feet. At 4 inches deep, it covers closer to 80 square feet.

The confusion happens because mulch is sold by the yard (volume) but you think about it in terms of coverage (area). A yard of mulch is always 27 cubic feet. The coverage changes based on how thick you lay it down.

Key Takeaways

  • One cubic yard of mulch equals 27 cubic feet and covers approximately 100 square feet at the standard 3-inch depth.
  • Thinner mulch (2 inches) covers more ground but may not retain moisture or suppress weeds as effectively as 3 inches.
  • Thicker mulch (4 inches or more) covers less area but provides better weed suppression and moisture retention.
  • To find how many yards you need, measure your bed in square feet, decide your desired depth, and use a straightforward calculation or online calculator.

How to calculate the yards you need

Start by measuring the length and width of each bed in feet, then multiply to get square footage. If your bed is 10 feet long and 4 feet wide, that is 40 square feet. Do this for every bed you plan to mulch.

Next, decide your depth. Three inches is standard for ornamental beds and vegetable gardens. Two inches works for pathways or if you are refreshing existing mulch. Four inches or deeper is useful for heavy weed pressure or around new plantings.

Use this formula: (square feet × depth in inches) ÷ 324 = cubic yards needed. For a 40-square-foot bed at 3 inches deep: (40 × 3) ÷ 324 = 0.37 yards. For a 100-square-foot bed at 3 inches: (100 × 3) ÷ 324 = 0.93 yards, so you would order 1 yard.

Many mulch suppliers and garden centers have online calculators where you enter square footage and depth, and they tell you the yards. This saves the math and accounts for settling and compaction.

Why depth matters for mulch performance

Mulch does three jobs: it suppresses weeds, retains soil moisture, and moderates soil temperature. All three work better at greater depth, but there is a practical limit.

At 2 inches, mulch provides light weed suppression and some moisture retention. It looks thin and may need refreshing every year. Use 2 inches if you are topping off existing mulch or if you have a tight budget and do not have heavy weed pressure.

At 3 inches, mulch blocks most weed seeds from reaching soil and keeps moisture in well. This is the depth most landscapers recommend and what most homeowners use. It lasts about 18 months before settling noticeably.

At 4 inches or deeper, mulch performs best at weed suppression and moisture retention, but it can trap moisture against tree trunks and plant stems, which invites rot and fungal problems. Never pile mulch directly against the base of a tree or shrub. Leave a 2 to 3-inch gap between the mulch and the stem.

Common mistakes when ordering mulch by the yard

The most frequent error is underestimating how much you need. Mulch settles and compacts over time, especially in the first few weeks. What looks like a full 3 inches when freshly spread may be 2 inches within a month. Many people order one yard thinking it will cover a 100-square-foot bed, then find they need more after settling.

Another mistake is confusing cubic yards with square yards. A square yard is a flat 9-foot-by-9-foot area with no depth—it is not a mulch measurement. Mulch is always sold in cubic yards (volume), not square yards.

A third error is not accounting for the shape of your beds. Irregular or curved beds waste more mulch at the edges than rectangular ones. If your beds are oddly shaped, add 10 to 15 percent to your calculated total.

Mulch types and whether they affect volume

Mulch comes in several forms: wood chips, shredded bark, pine straw, rubber, and compost blends. A cubic yard is a cubic yard regardless of type—the volume does not change. However, different mulches have different weights and densities, and they settle at different rates.

Hardwood mulch (made from mixed hardwoods) is denser and settles less than softwood mulch. Pine straw is lighter and fluffier, so it may look like more coverage initially but settles faster. Rubber mulch does not settle or decompose, so what you spread stays at that depth.

For coverage purposes, assume all organic mulches (wood, bark, straw) settle about 20 to 30 percent in the first season. Order slightly more than your calculation suggests, or plan to top off beds in spring.

Delivery and storage considerations

When mulch is delivered, it often arrives in a loose pile. A cubic yard of loose mulch takes up more space than 27 cubic feet because of air pockets. The pile may look enormous compared to what you expected. This is normal. As you spread it, it compacts and the volume shrinks.

If you cannot spread mulch when ready, keep it in a pile in a shaded area. Mulch can heat up and decompose quickly in direct sun, especially if it is wet. Wet mulch is heavier and harder to spread, so let it dry slightly if it arrives soaked.

For small projects, you can buy mulch by the bag at garden centers. A standard 2-cubic-foot bag covers about 8 square feet at 3 inches deep. To equal one cubic yard, you would need roughly 13 to 14 bags, depending on how full they are.

Frequently Asked Questions

How much does a yard of mulch weigh?

A cubic yard of mulch typically weighs 400 to 800 pounds, depending on the type and moisture content. Hardwood mulch is heavier (600 to 800 pounds) than softwood or pine straw (400 to 600 pounds). Wet mulch weighs significantly more than dry mulch. Check with your supplier for the exact weight of what you are ordering.

Can I order a partial yard of mulch?

Many suppliers sell mulch in half-yard or quarter-yard increments, though some have a minimum order. Prices per yard are usually lower for full yards, so ordering 1 yard is often cheaper than ordering 0.5 yards. Call your local mulch supplier to ask about minimums and partial-yard pricing.

How long does mulch last before I need to replace it?

Organic mulches (wood, bark, straw) break down over time and typically last 12 to 18 months before they need refreshing. Rubber mulch lasts much longer—5 to 10 years—but does not add organic matter to soil. In year two, you can often top off with a fresh 1 to 2 inches rather than removing the old mulch entirely.

What is the difference between a yard and a ton of mulch?

A yard is a volume measurement (27 cubic feet). A ton is a weight measurement (2,000 pounds). Some suppliers sell mulch by the ton instead of the yard. The conversion depends on mulch type and moisture, so ask your supplier how many yards equal one ton for their specific product.

Do I need to remove old mulch before spreading new mulch?

No. If old mulch is still in decent condition, you can spread new mulch on top. However, if old mulch is matted, moldy, or more than 2 years old, rake it out first. Layering fresh mulch over decomposed mulch can create a thick, waterlogged mat that traps moisture and invites fungal problems.