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Find the cubic yards of mulch needed for a bed or landscape area.
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Mulch calculator guide
Mulch is spread thin over a wide area, so a small change in depth makes a big difference to how many bags or yards you buy. This calculator multiplies the bed length and width in feet by the depth in inches converted to feet, adds an allowance for settling and uneven spreading, and gives the result in cubic yards, the unit bulk mulch is delivered in, plus cubic feet for comparing with bagged product. The 3 in default is the depth most extension services recommend for suppressing weeds and holding moisture around shrubs and perennials; use 2 in for annual beds and thinner around trunks. For irregular beds, split the area into rectangles and add the results, or measure the longest and widest points and accept a slight overestimate. The output is a volume; bag counts depend on the bag size you buy, and bulk suppliers usually sell in half-yard or full-yard increments.
Volume (ft³) = length (ft) × width (ft) × depth (in) ÷ 12 × (1 + waste ÷ 100). Volume (yd³) = ft³ ÷ 27. Bags = ft³ ÷ bag size (ft³), rounded up.
Worked example: a 20 ft × 10 ft bed covers 200 sq ft. At 3 in deep the mulch volume is 200 × (3 ÷ 12) = 50 ft³, and with a 10% allowance for settling it becomes 50 × 1.10 = 55 ft³. That converts to 55 ÷ 27 = 2.04 cubic yards, or 1.56 m³. In bags, 55 ÷ 2 = 27.5, so 28 bags of 2 ft³ mulch, or 55 ÷ 3 = 18.3, so 19 bags of 3 ft³. A bulk delivery would be rounded to 2 or 2.5 yards. The calculator shows 2.04 yd³.
Enter length and width in feet and depth in inches; the result is cubic yards, with cubic feet and cubic metres shown as well. One cubic yard is 27 cubic feet, which equals 13.5 bags of 2 ft³ or 9 bags of 3 ft³. For metric beds, 1 m² at 7.5 cm deep needs 0.075 m³; 1 yd³ is 0.765 m³. Convert inch fractions of length to decimal feet before entering.
The mulch calculator returns a quantity to buy, not a guarantee of coverage. Substrate condition, waste from cuts, spillage, and settling all push real consumption above the theoretical figure, which is why most trades order a margin on top. Check the coverage rate printed on the product you actually purchase, because it varies between brands and mixes. On this page the figure rests entirely on length, width, depth and waste allowance, so start there if the mulch calculator returns something you did not expect.
Good to know: the 80 lb bag row in the results uses a concrete bag yield and has nothing to do with mulch; count mulch bags from the cubic feet figure instead. Depth is the value people misjudge most: 4 in instead of 3 in adds a third to the order. Keep mulch 2–3 in away from trunks and stems, and refreshing an existing bed usually needs only 1–2 in on top, not the full depth. Bulk yards are loose volume and settle 10–20% within a season.
Construction quantities are planning estimates. Confirm product yield, waste, site conditions, structural requirements, and local code with the supplier or qualified professional.
Sources
How it works
Find the cubic yards of mulch needed for a bed or landscape area. This tool explains the calculation so you can adjust the assumptions to match your situation.
Worked example
With Length = 20 ft · Width = 10 ft · Depth = 3 in · Waste allowance = 10 % → 2.04 yd³ (recommended slab volume including waste). Change an input above and this example updates with your numbers.
Common questions
At 3 inches deep, 200 sq ft needs 50 cubic feet of mulch, about 1.85 cubic yards, or 2.04 yards with a 10% allowance. That is 28 bags of 2 cubic feet or 19 bags of 3 cubic feet. At 2 inches deep the requirement drops to 1.23 yards.
A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 ft³ mulch or 9 bags of 3 ft³. Bulk mulch by the yard is usually cheaper than bags once you need more than about 10 bags.
Spread 2–3 inches of bark or wood mulch around shrubs and perennials, 3 inches for weed suppression, and 1–2 inches when topping up an existing layer. Keep it a few inches away from tree trunks and plant stems.
One cubic yard covers 108 sq ft at 3 in deep, 162 sq ft at 2 in, and 324 sq ft at 1 in. Divide your bed area by those figures to estimate yards before allowance.
Break the bed into rectangles and triangles, calculate each, and add them, or pace the longest length and widest width and treat it as a rectangle for a slight overestimate. Curved beds are often 80–90% of the bounding rectangle.