Mulch calculator
Measure the bed, choose the depth you need to add, and compare bulk cubic yards with whole bags. Use the same takeoff whether you are refreshing a front bed or planning several beds for a customer.
The interactive calculator requires JavaScript. The formula and worked example below are available without it. No sign-up is required.
How to use this calculator
- Measure the area actually receiving mulch. Exclude walks and hard surfaces.
- Check existing mulch, then enter only the new depth you need.
- Choose your bag size or use the bulk volume. Confirm the order with your supplier.
The formula
Cubic yards = square feet × added depth in inches ÷ 324. Apply your extra allowance, then divide cubic feet by the volume per bag and round up.
Worked example
A 20 × 10 ft bed receiving 3 inches of mulch needs 50 cubic feet, or about 1.852 cubic yards. With no extra allowance, that is 25 two-cubic-foot bags. This is a math example, not a depth recommendation for every plant.
Top up the bed, not the trunk
Existing mulch counts toward the finished layer. Maryland Extension describes a 2–3 inch layer for trees and shrubs and advises keeping it away from the trunk. Check the needs of your planting before choosing the added depth.
Measure curved and separate beds
Break irregular beds into rectangles or circles, subtract unmulched areas, and add the areas together. Enter that total as measured square feet. Overlapping shapes should only be counted once.
Bags versus bulk delivery
The calculator shows volume and whole bags; it does not assume a supplier price. Compare delivery, bag handling, access to the beds, and the space available for a bulk drop before ordering.
Common questions
How many 2-cubic-foot bags are in a cubic yard?
One cubic yard is 27 cubic feet, so it equals 13.5 two-cubic-foot bags. Buy 14 whole bags if you need at least one cubic yard.
Should I add 3 inches on top of old mulch?
Enter only the additional depth needed for the finished layer. Check the existing mulch first; adding a full new layer every time can bury roots or pile material against plants.
Does the allowance include installation labor?
No. It adds material volume only. Access, bed preparation, edging, delivery, and installation are separate planning items.
Sources & method
Calculations use the formulas shown above. These references inform the planning guidance; they do not endorse this tool. References checked on .
Keep planning
- Topsoil & raised bed calculator
- Contractor job cost & margin calculator
- Explore mulch installation in Cincinnati
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