Mulch Calculator
To calculate mulch, multiply length × width in feet by the depth in inches and divide by 324 for cubic yards: one cubic yard covers 108 sq ft 3 inches deep. For example, a 10 × 10 ft bed 3 inches deep needs 0.93 cubic yards, or 13 bags of 2 cu ft.
How to calculate mulch
- Measure the area. Measure the length and width of each bed in feet and multiply them for square feet. For a round bed, measure the diameter.
- Choose a depth. Garden beds usually take 2 to 4 inches of mulch. Under play equipment, mulch is safety surfacing and goes much deeper: at least 9 inches for home equipment up to 8 feet high.
- Find the cubic yards. Multiply the square feet by the depth in inches and divide by 324, which is 12 inches × 27 cubic feet. For cubic feet, divide by 12 instead.
- Count bags. Divide the cubic feet by the bag size, such as 2 or 3 cu ft. A 40 lb bag of rubber mulch holds 1.50–1.55 cubic feet, and a 2,000 lb pallet 75–77 cubic feet.
- Round up. Round up to whole bags, or to the next half cubic yard for bulk mulch.
Worked example: a 10 × 10 ft bed 3 inches deep: 100 sq ft × 3 ÷ 324 = 0.93 cubic yards, or 25 cubic feet. That's 13 bags of 2 cu ft, 9 bags of 3 cu ft, or 17 bags of 40 lb rubber mulch (645–667 lb).
How many square feet does a yard of mulch cover?
A cubic yard of mulch is 27 cubic feet, so it covers 324 sq ft 1 inch deep: divide 324 by the depth in inches. At 3 inches, a cubic yard covers 108 sq ft. Bags work the same way from their cubic feet: a 2 cu ft bag covers 24 sq ft 1 inch deep, or 8 sq ft 3 inches deep.
| Depth | 1 cubic yard | 2 cu ft bag | 3 cu ft bag |
|---|---|---|---|
| 1 in | 324 sq ft | 24 sq ft | 36 sq ft |
| 2 in | 162 sq ft | 12 sq ft | 18 sq ft |
| 3 in | 108 sq ft | 8 sq ft | 12 sq ft |
| 4 in | 81 sq ft | 6 sq ft | 9 sq ft |
| 6 in | 54 sq ft | 4 sq ft | 6 sq ft |
Rubber mulch covers the same area per cubic yard; for its bags and pallets, see rubber mulch bags, pallets and weight.
How deep should mulch be?
For garden beds, Iowa State University Extension says 2 to 4 inches of mulch is generally effective, with coarse mulches such as wood chips at the deeper end and fine ones such as grass clippings at the shallower end. Oklahoma State University Extension recommends 3 inches of coarse mulch and 2 inches of fine mulch.
Under swings, slides and climbers, mulch is safety surfacing rather than a garden layer, and it has to be far deeper: see playground mulch depth.
Rubber mulch: bags, pallets and weight
Rubber mulch is sold by weight, and its makers also state the volume: a 40 lb bag holds 1.50–1.55 cubic feet, and a 2,000 lb pallet or super sack 75–77 cubic feet, about 50 bags. That makes rubber mulch about 25.8–26.7 lb per cubic foot, or 697–720 lb per cubic yard. A cubic yard is 17.4–18.0 bags, and a pallet is 2.78–2.85 cubic yards.
| Depth | 40 lb bag | 2,000 lb pallet |
|---|---|---|
| 1 in | 18.0–18.6 sq ft | 900–924 sq ft |
| 2 in | 9.0–9.3 sq ft | 450–462 sq ft |
| 3 in | 6.0–6.2 sq ft | 300–308 sq ft |
| 4 in | 4.5–4.7 sq ft | 225–231 sq ft |
| 6 in | 3.0–3.1 sq ft | 150–154 sq ft |
Each range runs from the smaller pack size to the larger one. If your bag or pallet lists a different volume, divide the calculator's cubic feet by that volume.
Playground mulch depth
Under play equipment, mulch cushions falls, and the U.S. Consumer Product Safety Commission (CPSC) sets how deep it should be. Its depths are far greater than the 3 inches some rubber mulch sellers suggest for home playgrounds.
- Home playgrounds: the CPSC's Outdoor Home Playground Safety Handbook calls for at least 9 inches of loose fill such as wood mulch, wood chips, engineered wood fiber or shredded rubber mulch under equipment up to 8 feet high. An initial fill of 12 inches compresses to about 9 inches over time. For equipment less than 4 feet high, use at least 6 inches.
- Public playgrounds: the CPSC's Public Playground Safety Handbook lists the depths below for loose fill that hasn't been impact-tested. Rubber mulch doesn't compress the way wood does, but it can still be displaced, so keep it at depth. Don't use wood mulch made from CCA-treated (chromated copper arsenate) wood.
- Tested products: playground rubber mulch should meet ASTM F3012, and engineered wood fiber ASTM F2075. For impact-tested products, follow the maker's stated depth.
| Mulch | Installed | Compressed | Max fall height |
|---|---|---|---|
| Rubber mulch | 8 in | 6 in | 10 ft |
| Wood mulch (non-CCA) | 12 in | 9 in | 7 ft |
| Wood chips | 12 in | 9 in | 10 ft |
For example, a 20 × 20 ft play area filled 12 inches deep with wood mulch takes 14.81 cubic yards, or 200 bags of 2 cu ft. Rubber mulch compresses less, so at 9 inches deep it takes 11.11 cubic yards: 194–200 bags of 40 lb, or 3.9–4.0 pallets.
Other materials
Pea gravel and sand can also go under play equipment, at their own depths: see the pea gravel calculator and the sand calculator. To top up a bed with soil before mulching, use the dirt calculator.
To convert any volume between cubic yards, cubic feet and cubic meters, use the cubic yard calculator.
Frequently asked questions
How many square feet does a yard of mulch cover?
One cubic yard of mulch (27 cubic feet) covers 324 sq ft 1 inch deep, so divide 324 by the depth in inches: 162 sq ft at 2 inches, 108 sq ft at 3 inches and 81 sq ft at 4 inches.
How much rubber mulch do I need?
Multiply the area in square feet by the depth in inches and divide by 12 for cubic feet, then divide by 1.50–1.55 for 40 lb bags, or by 75–77 for 2,000 lb pallets. A 10 × 10 ft area 3 inches deep is 25 cubic feet: 17 bags of 40 lb, weighing 645–667 lb.
How do you calculate mulch?
Multiply the area in square feet by the depth in inches and divide by 324 for cubic yards. A 10 × 10 ft bed 3 inches deep needs 100 × 3 ÷ 324 = 0.93 cubic yards, or 13 bags of 2 cu ft.
How much does a 40 lb bag of rubber mulch cover?
A 40 lb bag of rubber mulch holds about 1.50–1.55 cubic feet, so it covers 9.0–9.3 sq ft 2 inches deep, 6.0–6.2 sq ft 3 inches deep or 3.0–3.1 sq ft 6 inches deep.
How deep should you lay rubber mulch?
Under home playground equipment up to 8 feet high, the U.S. Consumer Product Safety Commission (CPSC) calls for at least 9 inches of loose fill, including shredded rubber mulch, and at least 6 inches under equipment less than 4 feet high. Its public playground handbook lists rubber mulch at 8 inches installed and 6 inches compressed, for falls up to 10 feet.
How many inches of mulch for a playground?
The U.S. Consumer Product Safety Commission's home playground handbook calls for at least 9 inches of wood mulch, wood chips or shredded rubber under equipment up to 8 feet high. Loose fill compresses, so fill about 12 inches to keep 9. Its public playground handbook lists wood mulch and wood chips at 12 inches installed and 9 inches compressed.
How many bags of mulch is 4 yards?
4 cubic yards of mulch is 108 cubic feet (4 × 27), which is 54 bags of 2 cu ft or 36 bags of 3 cu ft.
Related calculators
Sources and methodology
Volumes use (length × width × depth) ÷ 27 with all measurements in feet; with the depth in inches, that's square feet × inches ÷ 324. Bags are cubic feet ÷ the bag's cubic feet, rounded up. Rubber mulch uses its makers' stated sizes: a 40 lb bag holds 1.50–1.55 cubic feet and a 2,000 lb pallet 75–77 cubic feet, which is why rubber mulch results show a range; its weight (25.8–26.7 lb per cubic foot) comes from the same figures. Wood mulch is sold by volume, and no primary source for its weight was found, so the calculator doesn't estimate it. Bed depths are from Iowa State University Extension and Oklahoma State University Extension; playground depths are from the CPSC's home and public playground handbooks. Bulk orders are rounded up to the next half cubic yard.
- RubberMulch.com: Playsafer rubber mulch calculator (40 lb = 1.55 cu ft; 2,000 lb = 77 cu ft)
- GroundSmart Rubber Mulch: coverage calculator (1.5 cu ft bags; 75 cu ft super sacks and pallets)
- Rubber Mulch Warehouse: mulch calculator (a pallet is about 2,000 lb, 75 cu ft, 50 bags)
- Iowa State University Extension and Outreach, Yard and Garden: "Using Mulch in the Garden"
- Oklahoma State University Extension: "All You Need To Know About Mulch"
- U.S. Consumer Product Safety Commission: Outdoor Home Playground Safety Handbook, Publication 324
- U.S. Consumer Product Safety Commission: Public Playground Safety Handbook, Publication 325 (July 2025), Table 2
- NIST Special Publication 811 (Guide for the Use of the SI), Appendix B.8: conversion factors