Mulch Calculator
Mulch for beds, tree rings and borders: cubic yards, cubic feet and bags (2 or 3 cu ft, liters) for rectangles, circles, triangles, rings or a list of beds, with weight by mulch type, bulk vs bag cost and delivery.
How it works
area: rectangle L × W · circle π × d² ÷ 4 · triangle b × h ÷ 2 · tree ring π × (D² − d²) ÷ 4 · cubic feet = area × depth(in) ÷ 12 · cubic yards = cubic feet ÷ 27 · bags = cubic feet × (1 + extra%) ÷ bag size, rounded up
The depth in inches is divided by 12 to get feet and multiplied by the bed’s area for cubic feet. Rectangles, circles, triangles and tree rings each have their own area formula, and List mode adds up several beds, each with its own depth if you like. Landscape yards sell by the cubic yard (27 cubic feet), and stores sell 2- or 3-cubic-foot bags, so both are shown. Bags are rounded up because a part-bag still has to be bought. The mulch type only changes the weight, which matters if you haul it yourself. With both prices filled in, the calculator compares the bagged cost with bulk plus delivery.
Worked example
A 12 × 4 ft bed mulched 3 inches deep: 12 × 4 × 0.25 = 12 cubic feet, which is 12 ÷ 27 = 0.44 cubic yards or 6 two-cubic-foot bags. At $4 a bag that is $24. Bulk at $35 a yard plus $50 delivery would be $65.56, so bags win for a bed this size.
Sources: Inch Calculator — bags per cubic yard and coverage by depth · Omni Calculator — mulch bag size, price and weight inputs
Frequently asked questions
How deep should mulch be?
2–3 inches is the standard for beds. That holds moisture and blocks weeds without smothering roots. Coarse bark nuggets can go 3–4 in, rubber mulch 1.5–3 in. Keep mulch a few inches back from trunks and stems, because "mulch volcanoes" rot bark.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it equals 13.5 two-cubic-foot bags or 9 three-cubic-foot bags. One 2-cu-ft bag covers 12 sq ft at 2 in deep or 8 sq ft at 3 in.
How much does a cubic yard of mulch weigh?
Dry wood mulch runs about 400–800 lb per yard depending on the wood. Fresh chips and wet loads can reach 800–1,000 lb, compost about 1,000 lb, and stone about 2,700 lb. A full-size pickup holds about 2 yards of light mulch level with the bed sides.
Is bulk mulch cheaper than bags?
Usually from about 2–3 cubic yards up. Bulk mulch often costs $25–$45 a yard against $3–$5 for a 2-cu-ft bag ($40–$70 a yard), but delivery fees and minimum orders make bags cheaper for small beds. Enter both prices to see the answer for your job.
How often does mulch need topping up?
Organic mulch breaks down, so plan on adding about an inch a year. Measure the depth that is left and enter just the difference.
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This calculator is for educational purposes. Double-check important results before acting on them.