Mulch Calculator
Work out how many cubic yards of mulch you need for a bed from its area and the depth you want, plus the bag count for 1.5, 2 and 3 cubic-foot bags.
Last updated: October 2026
Mulch Needed
1.85 cubic yards
Formula below · 1 source (extension.umn.edu) · Updated Oct 2026
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About this calculator
Mulch is sold by volume: in bulk by the cubic yard, or in bags of 1.5, 2 or 3 cubic feet. The calculator turns your bed area and depth into cubic yards:
cubic yards = area (sq ft) × depth (in) ÷ 12 ÷ 27
Dividing the depth by 12 converts inches to feet, so area × depth gives cubic feet, and there are 27 cubic feet in a cubic yard (3 × 3 × 3). The chart under the result converts the volume to bags of each common size, rounded up.
For an irregular bed, split it into rectangles, circles (3.14 × radius²) and triangles (½ × base × height), add up the areas and enter the total.
How deep?
University of Minnesota Extension recommends a layer about 2 to 4 inches deep for most organic mulches; thinner layers let weeds through, and much deeper layers can keep air and water from roots. Keep mulch a few inches away from tree trunks and plant stems. When you are only topping up an existing layer, enter the depth you are adding, not the total.
| Depth | Area covered by 1 cubic yard | Cubic yards per 100 sq ft |
|---|---|---|
| 1 inch | 324 sq ft | 0.31 |
| 2 inches | 162 sq ft | 0.62 |
| 3 inches | 108 sq ft | 0.93 |
| 4 inches | 81 sq ft | 1.23 |
| 6 inches | 54 sq ft | 1.85 |
How to use
Measure the bed's length and width in feet, multiply to get square feet, and enter that with the depth in inches. Example (the defaults): 200 sq ft at 3 inches is 200 × 3 ÷ 12 = 50 cubic feet, and 50 ÷ 27 = 1.85 cubic yards. That is 25 bags of 2 cubic feet or 17 bags of 3 cubic feet. Two beds of 20 × 6 ft and 15 × 4 ft add up to 180 sq ft; at 3 inches that is 45 cubic feet, or 1.67 cubic yards. Topping up 600 sq ft with 1 inch needs 50 cubic feet, 1.85 cubic yards.
Frequently asked questions
How much area does a cubic yard of mulch cover?
324 sq ft at 1 inch deep, 162 sq ft at 2 inches, 108 sq ft at 3 inches and 81 sq ft at 4 inches. The table below lists more depths.
How many bags of mulch make a cubic yard?
A cubic yard is 27 cubic feet, so it takes 13.5 bags of 2 cubic feet, 18 bags of 1.5 cubic feet or 9 bags of 3 cubic feet. Check the bag label for its volume.
How deep should mulch be?
About 2 to 4 inches for most beds, according to University of Minnesota Extension. Use the shallower end for fine mulches and around small plants, and keep mulch pulled back from tree trunks.
Should I order extra?
Bulk loads are usually sold in whole or half yards, so round up to the next amount the supplier sells. A little extra covers uneven ground and settling.
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Sources & references
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