Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate how many cubic yards, cubic feet, and bags of mulch your garden beds need.
This calculator converts a garden bed's area and your desired mulch depth into the amount of mulch to buy -- shown as cubic yards (for a bulk delivery), cubic feet, and a bag count at the standard 2 cubic foot bagged-mulch size most garden centers sell.
Enter your bed's total area in square feet and how deep you want the mulch layer. 2 to 4 inches is the generally recommended range for most landscape mulch -- thinner doesn't suppress weeds well, and much thicker can actually smother plant roots and encourage fungal growth against tree trunks and stems.
Cubic Yards = (Area in sqft × Depth in inches) ÷ 324
Same underlying area-times-depth-to-volume conversion used across this site's aggregate calculators (324 = 12in/ft × 27 cu ft/cu yd) -- mulch doesn't have a meaningful "weight" figure the way gravel or soil does for ordering purposes, since it's sold by volume, not weight.
Use this for any planting bed, tree ring, or landscaped border. For a bulk delivery (typically more cost-effective past a few cubic yards), order the cubic-yard figure; for smaller beds, the bag count tells you exactly how many bags to grab at the garden center.
Avoid piling mulch directly against tree trunks or plant stems ("volcano mulching") -- even at a correct average depth, mulch banked up against bark traps moisture and encourages rot and pests. Keep a small gap around trunks and stems regardless of your bed's overall depth.
Garden beds are rarely rectangles. Break the shape into simple parts: a rectangle for the straight section, a half circle for a rounded end (area is about 1.57 times the radius squared), and so on. For a tree ring, take the area of the outer circle and subtract the small circle around the trunk that you intend to keep clear. Enter the combined area in square feet. A hypothetical bed made of a 10ft x 8ft rectangle and a 4ft radius half circle has about 80 plus 25, so around 105 sqft.
If a bed already has mulch, do not lay a full new layer on top. Measure the existing depth, and enter only the extra depth you need to reach your target. Piling new mulch onto old can make the layer too thick for air and water to reach the soil. Rake the old layer to loosen it before adding a thin top-up.
Wood chips, shredded bark, and pine needles decompose at different rates and settle differently. Fine materials pack down more than chunky ones, so a shredded product may look thinner than expected after a rainfall. Because this tool calculates by volume only, the weight and price per bag are up to the product you choose.
2 to 4 inches is the generally recommended range -- enough to suppress weeds and retain soil moisture without smothering plant roots or trapping excess moisture against stems.
It depends on your chosen depth -- at 3 inches, roughly 12-13 bags of 2 cu ft mulch; use this calculator with your actual area and depth for an exact count.
Bulk (by the cubic yard) is usually significantly cheaper per unit of coverage once you need more than a few cubic yards, but requires somewhere to dump a delivery and more labor to spread it yourself.
A cubic yard is 27 cubic feet, so it equals 13.5 bags of the 2 cubic foot size.
Not always. If the old layer is thin, loosen it and add a little on top. If it is thick, matted, or moldy, remove some before adding fresh mulch.
It depends on the mulch type and weather, since organic mulch breaks down over time. Check the depth each year and top up only if it has fallen below your target.