Calculators · Mulch Calculator
LandscapingMulch Calculator
Add one or more garden beds, set the depth in inches and get cubic yards, cubic feet and the number of bags.
Mulch needed
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How to calculate how much mulch you need
Mulch is sold by volume, so you need the volume of the layer you are going to spread. Find the area of each bed in square feet, then multiply by the depth. Because depth is usually given in inches, divide it by 12 to turn it into feet:
| Step | Formula |
|---|---|
| Area of a rectangle | length × width, in feet |
| Area of a circle | π × (diameter ÷ 2)² |
| Cubic feet | area in sq ft × depth in inches ÷ 12 |
| Cubic yards | cubic feet ÷ 27 |
| Shortcut | cubic yards = area in sq ft × depth in inches ÷ 324 |
The shortcut works because one cubic yard is 27 cubic feet and a foot is 12 inches, and 27 × 12 = 324. If your tape measure shows feet and inches, type the measurement as you read it, for example 10'6" or 10 ft 6 in. You can also pick inches, yards or meters from the unit menu, or choose “Area I already know” if you have the square footage.
How deep should mulch be?
University of Illinois Extension says that once settled, mulch should be 2 to 3 inches deep in a landscape bed. The Mississippi State University Extension article cited below, written in the first person, says its author thinks a 2- to 3-inch layer is sufficient for most applications and notes that deeper layers can delay the warming of the soil in spring and slow its cooling in fall. Illinois Extension also warns against piling mulch up around the trunk of a tree in a “volcano” shape.
Sources, checked October 2026: Mulch Madness and Landscape Mulch with Expectations (University of Illinois Extension), and Use mulch for beauty and weed, temperature control (Mississippi State University Extension).
How much does a cubic yard of mulch cover?
This table is pure geometry. A cubic yard is 27 cubic feet, so the area it covers is 324 divided by the depth in inches.
| Depth | Square feet per cubic yard |
|---|---|
| 1 inch | 324 |
| 2 inches | 162 |
| 3 inches | 108 |
| 4 inches | 81 |
How many bags of mulch do you need?
Divide the cubic feet you need by the size printed on the bag and round up. The calculator shows the three sizes below. We found them on product pages we opened in October 2026: Scotts Nature Scapes Color Enhanced Mulch in 1.5 cu ft, the same mulch in 2 cu ft and Johnson's Grade-A All Bark Cedar Mulch in 3 cu ft. Other brands may use other sizes, so read your label. If it differs, type it into “Your bag size”.
| Bag size | Sq ft at 2 in | Sq ft at 3 in | Sq ft at 4 in | Bags per cu yd |
|---|---|---|---|---|
| 1.5 cu ft | 9 | 6 | 4.5 | 18 |
| 2 cu ft | 12 | 8 | 6 | 13.5 |
| 3 cu ft | 18 | 12 | 9 | 9 |
The area a bag covers is 12 × its size in cubic feet ÷ the depth in inches. The Johnson's page says its 3 cu ft bag covers approximately 12 square feet at 3 inches deep, which matches the table.
Example: a rectangular bed and a round bed
A bed along a fence measures 20 ft by 4 ft and a round bed has a 6 ft diameter. You want 3 inches of mulch and plan to add 10% waste.
| Step | Operation | Result |
|---|---|---|
| Bed 1 | 20 × 4 | 80 sq ft |
| Bed 2 | π × 3² | 28.27 sq ft |
| Total area | 80 + 28.27 | 108.27 sq ft |
| Volume at 3 in | 108.27 × 3 ÷ 12 | 27.07 cu ft |
| With 10% waste | 27.07 × 1.10 | 29.78 cu ft |
| Cubic yards | 29.78 ÷ 27 | 1.10 cu yd |
| Bags of 2 cu ft | 29.78 ÷ 2 = 14.89, rounded up | 15 bags |
Mulch needed for common bed sizes at 3 inches
| Bed | Sq ft | Cu ft | Cu yd | 2 cu ft bags |
|---|---|---|---|---|
| 4 ft × 10 ft | 40 | 10 | 0.37 | 5 |
| 10 ft × 10 ft | 100 | 25 | 0.93 | 13 |
| 10 ft × 20 ft | 200 | 50 | 1.85 | 25 |
| 20 ft × 20 ft | 400 | 100 | 3.70 | 50 |
| 12 ft circle | 113.10 | 28.27 | 1.05 | 15 |
Frequently asked questions
How do I calculate how much mulch I need?
Multiply the length of the bed by its width to get square feet. Multiply that by the depth in inches and divide by 324 to get cubic yards. A 10 ft by 10 ft bed at 3 inches deep is 100 × 3 ÷ 324 = 0.93 cubic yards. The 324 comes from 27 cubic feet in a cubic yard times 12 inches in a foot.
How many square feet does a cubic yard of mulch cover?
It depends on the depth. A cubic yard covers 324 ÷ depth in inches, so 162 square feet at 2 inches, 108 square feet at 3 inches and 81 square feet at 4 inches.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so divide 27 by the size printed on the bag. That is 18 bags of 1.5 cubic feet, 13.5 bags of 2 cubic feet (buy 14) or 9 bags of 3 cubic feet.
How many square feet does a 2 cubic foot bag of mulch cover?
A 2 cubic foot bag covers 12 square feet at 2 inches deep, 8 square feet at 3 inches and 6 square feet at 4 inches. The rule is 12 × bag size in cubic feet ÷ depth in inches.
How deep should mulch be?
University of Illinois Extension recommends 2 to 3 inches once settled for a landscape bed, and a Mississippi State University Extension article says its author thinks a 2- to 3-inch layer is sufficient for most applications. Keep mulch from piling against tree trunks.
How do I calculate mulch for a circular bed?
Measure the diameter, halve it to get the radius and find the area with π × radius². A 6 ft circle is 3.1416 × 3² = 28.27 square feet. Then multiply by the depth as for any other bed. In this calculator, pick Circle and type the diameter.
Is it cheaper to buy mulch in bags or in bulk?
Compare the same unit. Bulk mulch is sold by the cubic yard and bags by the cubic foot, and one cubic yard is 27 cubic feet. Multiply the price of a bag by 27 and divide by its size in cubic feet to get the price per cubic yard, then compare it with the bulk price from your supplier.