Calculate the layer volume
Multiply area in square feet by depth in inches, then divide by 12 to obtain cubic feet. For irregular areas, measure simpler sections and add their volumes. Exclude paths and spaces you are not covering. The mulch layer is not the full depth of a raised bed.
Example: 120 square feet
At a selected depth of 2 inches, 120 × 2 ÷ 12 = 20 cubic feet. At 3 inches the target becomes 30 cubic feet. These are comparison scenarios rather than a depth recommendation for every plant or mulch. Check the intended use and supplier’s directions.
Compare bag sizes
For a 20 cubic foot target, ten 2 cubic foot bags match the volume. With 1.5 cubic foot bags, round 20 ÷ 1.5 up to 14 bags: you buy 21 cubic feet. The extra cubic foot comes from whole-bag rounding, not an added settling allowance.
Bags per cubic yard
One cubic yard contains 27 cubic feet. It equals eighteen 1.5 cubic foot bags exactly. Fourteen 2 cubic foot bags provide 28 cubic feet, slightly more than a yard. Always round the total purchase, and enter the actual bag capacity rather than assuming one standard size.
Use the tools and account for existing mulch
For a 12 × 10 foot rectangle at 2 inches depth, select inches in the raised-bed calculator and enter 144, 120 and 2. Transfer the 20 cubic foot result to bags. For a top-up, use only the additional depth. Compare the same material when evaluating bagged and bulk prices.
Frequently asked questions
Is one cubic yard thirteen 2 cubic foot bags?
No. Thirteen supply 26 cubic feet; fourteen supply at least 27.
Does the calculator choose mulch depth?
No. You choose the layer appropriate to the project.