Free mulch coverage calculator: enter bed size and depth to get cubic yards, bags needed, coverage per yard, and waste allowance.
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Measure the bed length and width in feet and the mulch depth you want in inches. The calculator finds the bed area, turns it into cubic feet and cubic yards, adds your settling and waste allowance, then rounds the bag count up so you never buy a fraction of a bag. One cubic yard covers 324 divided by the depth in inches square feet.
A rectangular bed is a shallow box. Its area is length times width in square feet. Multiply that area by the depth in feet, which is depth in inches divided by 12, to get cubic feet. Divide cubic feet by 27, because a cubic yard is 3 feet by 3 feet by 3 feet, to get cubic yards, the unit bulk suppliers use. The shortcut competitors quote is cubic yards equals square feet times depth in inches divided by 324, and it gives the same answer. A 20 foot by 10 foot bed at 3 inches is 200 square feet times 3 divided by 324, which is 1.85 cubic yards before waste. With the default 10 percent allowance that becomes 2.04 cubic yards, and at 2 cubic feet per bag that is 28 bags, rounded up.
Measure the bed at its longest length and widest width, in feet. For a curved bed, average the width or split the bed into rectangles and add the volumes. Enter the settled depth you want, not the fluffy height of a fresh pile. Pick the bag size printed on the label, usually 2 cubic feet, and keep the default 10 percent settling allowance on a new bed. Read cubic yards for a bulk order and bags for a bagged order, and compare the two before you buy.
Flower beds and garden beds do best at 2 to 3 inches after settling. That depth holds moisture and blocks weeds without starving roots of air. Tree rings work at 3 to 4 inches, shaped like a donut with mulch kept clear of the trunk, never piled against the bark in a volcano shape. Vegetable beds suit 2 inches, and paths can take 3 to 4 inches with edging to hold the material in place. Playground mulch is different: engineered wood fibre or rubber is installed much deeper, often 6 to 12 inches, under playground safety rules, so check the local standard rather than guessing.
One cubic yard covers about 324 square feet at 1 inch, 162 square feet at 2 inches, 108 square feet at 3 inches, and 81 square feet at 4 inches. One 2 cubic foot bag covers about 24 square feet at 1 inch, 12 at 2 inches, 8 at 3 inches, and 6 at 4 inches. Those coverage figures explain why depth matters more than area alone: the same 100 square feet needs 0.93 cubic yards at 3 inches but only 0.62 at 2 inches. Use the coverage per cubic yard result on this page to sanity check any supplier quote.
One cubic yard holds 27 cubic feet, so it equals 13.5 bags of 2 cubic feet, rounded up to 14 bags, or 9 bags of 3 cubic feet. Bagged mulch suits small beds, tight access, and weekend jobs with no delivery minimum. Bulk mulch by the cubic yard is usually much cheaper per cubic foot once the job passes about 2 cubic yards, and it avoids opening dozens of bags. Compare the two on your own prices: bulk cost is cubic yards times price per yard, while bagged cost is bags times price per bag, and a delivery fee can change the winner on a small order.
For an L-shaped bed, split it into two rectangles, calculate each, and add the totals. For a circular tree ring, use pi times radius squared for the area, then the same depth math. On a slope, keep the waste allowance at the high end, because loose mulch migrates downhill before it settles. Shredded hardwood and bark are the general garden choice, cedar resists insects near structures, dyed mulch holds colour longer, and rubber mulch lasts years but adds nothing to the soil and suits playgrounds, not vegetable beds. Organic mulch breaks down over the season, so plan a 1 to 2 inch top-up each year rather than a full replacement.
Ordering by area alone without depth is the most common mistake, followed by mulching deeper than 4 inches, which can suffocate roots and invite rot. Piling mulch against trunks and stems is another one: keep it several inches clear. Measuring depth on a fluffy fresh pile overstates the settled layer, so expect 20 to 30 percent settling in the first months for shredded material. Finally, check the bag size on the label, because 1, 1.5, 2, and 3 cubic foot bags all exist and change the bag count a lot.
Multiply length times width in feet for square feet, multiply by depth in inches divided by 12 for cubic feet, then divide by 27 for cubic yards. A 20 by 10 foot bed at 3 inches needs 50 cubic feet, or 1.85 cubic yards, before waste.
One cubic yard is 27 cubic feet, so it holds 13.5 bags of 2 cubic feet, rounded up to 14 bags, or 9 bags of 3 cubic feet. Divide your total cubic feet by your bag size and round up.
Use 2 to 3 inches after settling for most flower and garden beds, 3 to 4 inches for tree rings kept clear of the trunk, and 2 inches for a yearly refresh. Never go past 4 inches on planting beds.
At 3 inches deep, 100 square feet needs 25 cubic feet, or 0.93 cubic yards, which is 13 bags of 2 cubic feet before waste. At 2 inches it needs about 0.62 cubic yards, or 9 bags.
Usually yes on larger jobs. Bulk mulch is priced per cubic yard, while bagged mulch costs more per cubic foot, and the gap grows past about 2 cubic yards. Add any delivery fee before comparing.
Shredded hardwood or bark suits most beds, cedar suits areas near structures for insect resistance, dyed mulch holds colour, and rubber or engineered fibre suits playgrounds only where the safety standard calls for it.
Top-dress 1 to 2 inches each year when it thins below 2 inches or weeds break through. Plan a full refresh every 2 to 3 years for bark and wood chips, longer for rubber mulch.
Yes. Split an L-shaped bed into rectangles and add the volumes, use pi times radius squared for a circular tree ring, and use the average width for a curved bed. Add extra waste on slopes.
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