Mulch Calculator

Multiply the area in square feet by the depth in feet (inches ÷ 12) to get cubic feet. Divide by 27 for cubic yards, or by the bag size for bags, and round bags up. A 10 × 10 ft bed at 3 in is 100 × 0.25 = 25 cu ft, or 0.93 cu yd: 13 bags of 2 cu ft before any extra for settling. That is all the calculator does, for each area you add. (Source: Unit definitions)

Measure across the whole ring and across the bare circle you leave around the trunk. The area is π × (outer radius² − inner radius²). A ring 6 ft across with a 1.5 ft bare center is 26.5 sq ft; at 3 in deep that is 6.6 cu ft, or 4 bags of 2 cu ft. Choose “Ring around a tree” in the calculator to do this for you. (Source: Unit definitions)

For bags: the number of bags times the price per bag. For bulk: the cubic yards rounded up to the step your supplier sells in, times the price per yard, plus any delivery fee. Prices vary by store, region and season, so ScapeCalc uses the prices you enter rather than its own. Open “Add prices” in the calculator to see both totals side by side. (Source: Unit definitions)

A cubic yard is 27 cubic feet, so it takes 13.5 bags of 2 cu ft, or 9 bags of 3 cu ft. Stores sell whole bags, so buy 14 of the 2 cu ft size. Four cubic yards is 108 cu ft: 54 bags of 2 cu ft or 36 bags of 3 cu ft. (Source: Unit definitions)

A 2 cu ft bag covers 12 sq ft at 2 in deep, 8 sq ft at 3 in and 6 sq ft at 4 in. Twenty bags at 3 in cover about 160 sq ft; 25 bags cover about 200 sq ft. Divide the bag size in cubic feet by the depth in feet (inches ÷ 12). (Source: Unit definitions)

It depends on your prices and the delivery fee. When bulk costs less per cubic foot than bags, the delivery fee still makes bags cheaper on small jobs, and bulk wins past a break-even volume. Add your prices to the calculator to see both totals and where bulk starts to pay off. For scale, a 10 × 10 ft bed at 3 in needs 25 cu ft, about 0.93 cu yd. (Source: Unit definitions)

Piling it too deep or against trunks and stems. Illinois and UNL Extension recommend 2 to 4 in for most beds, and Illinois Extension warns that too much mulch can be harmful. Guides agree mulch should not touch the bark but differ on the gap: an inch or two (Purdue Landscape Report, University of Maryland Extension) to at least 4 in (Illinois Extension). (Sources: Illinois Extension; UNL Extension EC1274; Purdue Landscape Report; University of Maryland Extension)

For most beds, trees and shrubs, 2 to 4 in (Illinois Extension, UNL Extension). Fine or composted mulch can be thinner than coarse chips. UNL suggests 1 to 2 in around flowers and vegetables. Play areas need much more: see the playground questions below. (Sources: Illinois Extension; UNL Extension EC1274)

A rule of thumb for trees, used by the tree-planting group Casey Trees: a ring about 3 in deep, reaching 3 ft out from the trunk, with 3 in of bare ground left around the trunk. It is not a standard. Extension guides agree on keeping mulch off the bark but differ on the gap, from an inch or two (University of Maryland Extension) to at least 4 in (Illinois Extension). (Sources: Casey Trees; University of Maryland Extension; Illinois Extension)

UNL Extension says to mulch new plantings as soon as they go in, and to refresh existing beds in early spring, before leaves make the soil hard to reach. Mulch meant to protect plants over winter goes down after at least two hard freezes. The best month depends on where you live. (Source: UNL Extension EC1274)

Not always. UNL Extension says to rake the old layer and check its depth before adding more, and to break up any crust that sheds water. Good wood mulch may need only a light top-up each year, with full replacement every 2 to 4 years. Only add enough to reach the recommended depth: use “Top up an existing layer” in the calculator to buy just the difference. (Source: UNL Extension EC1274)

Straight onto the soil is fine; pull existing weeds first. UNL Extension does not recommend landscape fabric under mulch in most beds: weeds grow through it, seeds sprout in mulch on top, and roots get tangled in it. It recommends against plastic sheeting in beds, because it blocks air and water. (Source: UNL Extension EC1274)

No. UNL Extension says to keep mulch below the top of the concrete foundation, because mulch against wood or siding can lead to mold and insect damage. It suggests a band of rock or other inorganic mulch about 1 ft wide next to the foundation to discourage termites. (Source: UNL Extension EC1274)

Both. UNL Extension says to water the soil thoroughly before putting new mulch down, then water organic mulch once it is in place so it settles and holds together in wind and rain. (Source: UNL Extension EC1274)

It depends on the material: organic mulch breaks down and needs topping up. UNL Extension says good wood mulch may need only a light top-up each year and full replacement every 2 to 4 years, while pine straw breaks down slowly. Rock does not break down, but UNL notes it heats the area around plants and is hard to remove later. (Source: UNL Extension EC1274)

For a home play set with equipment up to 8 ft high, CPSC's home playground handbook says to keep 9 in of wood mulch or chips, and that 12 in put down will compress to about 9 in, so install about 12 in. For equipment under 4 ft, it says to keep at least 6 in. CPSC's separate public playground handbook (2025) uses a fall-height table that it says is not meant for home play sets. (Sources: CPSC Pub. 324; CPSC Pub. 325 (2025))

Surfacing made for playgrounds can be impact-tested: the maker states a depth and the fall height it protects to (ASTM F1292). CPSC’s home playground handbook refers to ASTM F1292 for surfacing requirements. Its 2025 public playground handbook, written for public playgrounds, prefers tested surfacing, says engineered wood fiber should meet ASTM F2075 and rubber mulch ASTM F3012, gives separate depths for untested wood mulch, wood chips and rubber, and says to avoid untested recycled-tire rubber where toddlers play. Ordinary landscape mulch is not tested for this. ScapeCalc names these standards as CPSC cites them; it has not reviewed them or tested any product. (Sources: CPSC Pub. 324; CPSC Pub. 325 (2025))

Under a home play set with equipment up to 8 ft, CPSC's home playground handbook says to keep 9 in of shredded rubber, and that 12 in of loose fill put down will compress to about 9 in, so ScapeCalc counts 12 in installed. CPSC's 2025 public playground handbook recommends less for public playgrounds: 6 in kept, 8 in installed, for falls up to 10 ft. That handbook says it is not meant for home play sets, so the home figure is used here. (Sources: CPSC Pub. 324; CPSC Pub. 325 (2025))

At a rough 26 lb per cubic foot, 2,000 lb is about 76.9 cu ft. That covers about 308 sq ft at 3 in, or 77 sq ft installed 12 in deep for a home play area. That density is an estimate from four product listings (about 25.6 to 26.7 lb per cu ft), not a standard, so use the weight and volume on your product. (Source: ScapeCalc, from product listings)

WSU Extension recommends against rubber mulch in gardens and landscapes. The reasons it gives: zinc can build up to levels toxic to plants, rubber is highly flammable, and it can leach chemicals as it breaks down. UNL Extension says shredded rubber is not widely recommended as a landscape mulch, and Purdue Extension says its long-term safety is still unclear, noting that heavy metals can leach out and that rubber can heat up enough to damage tender plants. For public playgrounds, CPSC’s 2025 public playground handbook says untested rubber mulch made from recycled tires may contain hazardous metals, and to use rubber mulch only if it meets ASTM F3012. (Sources: WSU Extension FS163E (archived, rev. 2021); UNL Extension EC1274; Purdue Extension; CPSC Pub. 325 (2025))