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Mulch calculator
Enter the bed size, the depth and the bag size on the label: the bags and the bulk cubic yards appear together, with the cost if you type a price.
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Mulch to buy
1.11 cu yd
1.11 cubic yards · 30.0 cubic feet over 120 square feet
| Bags of 2 cu ft | 15 |
| Bulk, in cubic yards | 1.11 |
One cubic yard covers 324 square feet one inch deep. Keep mulch a few inches away from stems and trunks. How this is calculated.
A planting bed 30 feet long and 4 feet wide, mulched 3 inches deep, takes 30 cubic feet of mulch: 1.11 cubic yards in bulk, 15 bags of 2 cubic feet or 10 bags of 3 cubic feet. Clemson Cooperative Extension gives the rule behind it: one cubic yard covers 324 square feet one inch deep, so 162 square feet at 2 inches and 108 at 3. Extension services put the right depth at 2 to 3 inches for fine wood and bark mulch, and the University of Florida IFAS advises no more than 3. At 2 inches the same bed needs 0.74 cubic yards. A cubic yard equals 14 bags of 2 cubic feet once you round up, 9 bags of 3 cubic feet or 18 bags of 1.5, which is the comparison that decides whether bulk delivery pays. Type the price of a bag and the calculator totals it.
The 324 square foot rule
A cubic yard is 27 cubic feet. Spread one inch thick, 27 cubic feet cover 27 times 12, or 324 square feet, the figure the Clemson Home and Garden Information Center prints in its mulch fact sheet. Everything else follows from it: divide 324 by your depth in inches to see how far a yard goes, or multiply your bed area by the depth in inches and divide by 324 to see how many yards you need. The calculator does the second sum, then divides the cubic feet by the volume on the bag, rounding up because a half bag is still a bag at the register.
| Bed area | Cu yd at 2 in | 2 cu ft bags at 2 in | Cu yd at 3 in | 2 cu ft bags at 3 in | 3 cu ft bags at 3 in |
|---|---|---|---|---|---|
| 50 sq ft | 0.31 | 5 | 0.46 | 7 | 5 |
| 100 sq ft | 0.62 | 9 | 0.93 | 13 | 9 |
| 200 sq ft | 1.23 | 17 | 1.85 | 25 | 17 |
| 300 sq ft | 1.85 | 25 | 2.78 | 38 | 25 |
| 500 sq ft | 3.09 | 42 | 4.63 | 63 | 42 |
| 1,000 sq ft | 6.17 | 84 | 9.26 | 125 | 84 |
How deep to spread it
Clemson says many wood and bark mulches, made of fine particles, should not go deeper than 2 to 3 inches. The University of Florida IFAS Gardening Solutions page recommends 3 inches and a 2 to 3 inch layer around established trees, shrubs and bedding plants, and tells readers not to apply more than 3. More is not better here, and both services draw the line at the same place. That is why the calculator suggests 2 to 3 inches in the depth field and starts at 3.
Keep it off trunks, stems and walls
Both extension services warn against piling mulch against plants. Clemson asks for 2 to 3 inches of clearance around the stems of woody plants and 6 to 12 inches from the walls of buildings, so leave a strip of bare soil or gravel along the foundation. UF/IFAS calls the cone of mulch heaped around a trunk "volcano mulching" and says it holds moisture and encourages rot; for large plants and trees it advises keeping mulch about a foot from the base. A ring 8 feet across around a young tree, 3 inches deep, takes 12.6 cubic feet, or 7 bags of 2 cubic feet, before you subtract the bare circle at the trunk.
Topping up an old bed
Mulch breaks down, so most beds need a refresh rather than a full layer. Push a trowel into the bed and measure what is left, then enter only the depth you are adding. Bringing the 30 by 4 foot bed back up by one inch takes 10 cubic feet, 5 bags of 2 cubic feet, a fraction of a new installation. If the old layer has matted into a crust that sheds water, break it up with a rake before you add more.
Bags or a bulk load
Bags are clean, easy to carry to a back corner and simple to store, and they win on small beds. Bulk mulch from a landscape yard is sold by the cubic yard and dumped in the driveway, so it pays when the job is large: the 1,000 square foot border in the table needs 9.3 cubic yards at 3 inches, or 125 bags of 2 cubic feet. Compare the yard's delivered price per cubic yard with 14 times your bag price; that one multiplication answers the question for your area. Check the bag label too, since sizes vary between 1.5, 2 and 3 cubic feet and the calculator lets you pick each one.
Paying someone to spread it
BLS counted 952,640 landscaping and groundskeeping workers in May 2025, with a mean wage of $20.33 an hour and the middle half between $17.40 and $22.52. A landscaping company bills above that wage for its truck, equipment and insurance, and some quote mulch installed per cubic yard; the yards on this page let you check that figure. If the bed borders a gravel path, the gravel calculator sizes the stone with the same length, width and depth inputs.