ReckonBoxHow much mulch a bed swallows
The amount of mulch you need is the bed area times the depth in feet, divided by 27 for cubic yards. A 200 square foot bed at 3 inches deep works out to 50 cubic feet, or 1.85 cubic yards.
Depth is the part people underestimate. A bed does not look like it holds much until you spread the first bag and it vanishes. At 3 inches, that 200 square foot bed takes 25 two-cubic-foot bags, and 25 bags is a full car trunk and then some. The tool also shows the shortcut the nurseries use: one cubic yard covers 108 square feet at 3 inches, so a 200 square foot bed lands just under 2 yards.
Bags or bulk
One cubic yard of mulch holds 14 bags at 2 cubic feet, 9 bags at 3 cubic feet, or 18 bags at 1.5 cubic feet. A cubic yard is 27 cubic feet, so the bag count is just 27 divided by the bag size.
The choice between bags and a bulk delivery usually turns on quantity. Under a dozen bags, bagged mulch is easy: it fits in a car, stores in the garage, and lets you touch up thin spots later. Past that, a bulk yard delivered to the driveway is cheaper per cubic foot and saves a lot of trips, at the cost of a pile you have to move by wheelbarrow before it kills the grass under it.
Depth changes everything
The same bed can need one yard or two, and depth alone decides which. One cubic yard covers 324 square feet at 1 inch, but only 108 at 3 inches and 81 at 4. Spread a fixed amount of mulch thinner and it goes further; pile it deeper and it disappears faster.
| One cubic yard covers | Square feet |
|---|---|
| At 1 inch | 324 |
| At 2 inches | 162 |
| At 3 inches | 108 |
| At 4 inches | 81 |
For depth itself, 2 to 3 inches refreshes an established bed, and 3 to 4 inches suits a new bed or the ring around a tree, where the extra depth holds moisture and smothers weeds. Piling much past 4 inches works against you, trapping water on stems and starving roots of air.
Where the numbers come from
Area is length times width. Depth in inches converts to feet by dividing by 12, and area times depth in feet gives cubic feet, which divided by 27 is cubic yards. Bags are the cubic feet divided by the bag size, rounded up, since you buy whole bags. The 10 percent settling allowance scales both, because fresh mulch is fluffy and packs down over the first few weeks.
What this does not cover
This sizes loose mulch for a bed of a given area and even depth. It does not price bulk against bagged for you, since delivery fees and per-yard rates vary by supplier and distance. It also assumes an ordinary wood or bark mulch; rubber, stone, and rice hull mulches sell by different bag volumes and cover differently, and a steep slope or a bed you want mounded will use more than the flat calculation says. The volume is the estimate, not the landscaping plan.
Order the extra 10 percent, because the trip back for one more bag always costs more than the bag.
Frequently asked questions
How much mulch do I need? Multiply the bed area by the depth in feet, then divide by 27 for cubic yards. A 200 square foot bed at 3 inches deep is 50 cubic feet, or 1.85 cubic yards. In 2 cubic foot bags, that is 25 bags. A shortcut is that one cubic yard covers 108 square feet at 3 inches, so 200 square feet needs just under 2 yards.
How many bags of mulch are in a cubic yard? One cubic yard holds 14 bags at 2 cubic feet, 9 bags at 3 cubic feet, or 18 bags at 1.5 cubic feet, since a cubic yard is 27 cubic feet. Bulk mulch by the yard is usually cheaper than bags once you pass roughly a dozen bags, though bags are easier to haul in a car and store for touch-ups.
How deep should mulch be? Spread mulch 2 to 3 inches deep to refresh an established bed and 3 to 4 inches for a new bed or around trees, where more depth holds moisture and blocks weeds. Deeper than about 4 inches can smother roots and hold too much water against stems. Depth changes the volume directly, so a 4 inch layer uses a third more mulch than a 3 inch one.
How much area does a cubic yard of mulch cover? One cubic yard of mulch covers 324 square feet at 1 inch deep, 162 square feet at 2 inches, 108 at 3 inches, and 81 at 4 inches. The deeper you spread it, the less ground a yard covers, which is why the same bed can need one yard or two depending only on the depth you choose. This tool shows the coverage for your depth.
Should I add extra mulch for settling? Add about 10% extra, because fresh mulch is fluffy and settles and migrates over the first weeks, and a bed with an irregular edge uses a little more. Running slightly over means you can top up thin spots rather than making a second trip. This tool applies your settling allowance to both the cubic yards and the bag count.