How to calculate your mulch project
Mulch coverage depends on bed area and finished depth. Use this calculator for one continuous bed, then repeat and add the results when your project contains separate areas.
Need the surface area? Measure your outdoor project on our satellite map →
- Measure the bed at its widest practical dimensions.
- Select rectangle or circle and enter the measurements.
- Enter the intended finished depth and add a settling allowance.
Formula
The calculation
Area × depth = cubic feet. Divide cubic feet by 27 for cubic yards, or divide by the labeled bag size for a bag count.
Worked example
A 12 × 8 ft bed at 3 inches deep with 10% extra requires about 0.98 cubic yards, or approximately 14 two-cubic-foot bags.
The result is a planning estimate. Round purchasing quantities up to available package sizes and confirm the exact product specifications.
Material assumptions
- Bag count uses standard 2-cubic-foot bags.
- Existing mulch is not subtracted.
- Depth is the finished, evenly spread layer.
Read the complete calculator methodology for unit conversions, rounding rules, and limitations.
Why the waste factor matters
A waste or extra-material percentage allows for real-world variation: irregular edges, cuts, compaction, settling, spillage, and measurement error. Ten percent is a useful starting point, not a universal rule. Increase or reduce it according to the material, layout, and supplier guidance.
Unit conversions used
Questions
Mulch Calculator FAQ
How deep should mulch be?
Two to three inches is common for established beds. Keep mulch away from trunks and stems, and follow local fire-safety guidance.
How many 2-cubic-foot bags equal one cubic yard?
A cubic yard contains 27 cubic feet, so it equals 13.5 two-cubic-foot bags. Since stores sell whole bags, round up to 14.
Should I remove old mulch first?
If the existing layer is still deep, measure it before adding more. Rake compacted material and avoid creating an excessively thick layer.