Enter the bed size and depth.
Bag sizes vary by brand; check the label. Bulk is sold by the cubic yard; 1 cubic yard is 27 cu ft.
How to measure garden beds
Measure each bed's length and its average width, and multiply. A bed that curves from 2 ft to 6 ft wide averages about 4 ft. Add the beds together, or run the calculator once per bed and add the results. For a circle around a tree, multiply the radius by itself and by 3.14, then enter that area as length × 1.
How deep to spread it
| Job | Typical depth |
|---|---|
| Fresh mulch on bare beds | 3 in |
| Topping up last year's mulch | 1–2 in |
| Topsoil under new sod | 4 in |
| New planting bed, triple mix | 6 in |
Keep mulch a few inches back from tree trunks and shrub stems; piled against the bark it holds moisture and invites rot. Keep soil and mulch below the house's siding and waterproofing line, too.
Bulk or bags?
Bags make sense for small jobs and tight access. Past about two cubic yards, bulk delivery is usually cheaper and much less plastic, but it needs a spot on the driveway and a tarp underneath. One cubic yard is 27 cubic feet, which is about thirteen 2 cu ft bags.
Mistakes to avoid
- Too deep. More than about 3 to 4 inches of mulch can starve roots of air and water.
- Mulch on weeds. Weed and edge the beds first; mulch over established weeds only hides them for a few weeks.
- Soil against the house. Raising beds beside the foundation can send water toward the basement. See drainage and grading.
Would rather hand it off? Garden maintenance includes edging and mulching, and garden design builds new beds with proper soil prep.
Questions about this tool
How much mulch do I need?
Multiply the bed area by the depth. A 100 sq ft bed at 3 inches needs 25 cubic feet, about 0.93 cubic yards or thirteen 2 cu ft bags. Most beds need 3 inches on bare soil and 1 to 2 inches as a yearly top-up. Weed and edge the beds before you spread it.
How deep should mulch be?
About 3 inches on bare beds and 1 to 2 inches when topping up, which is enough to block light from weed seeds and hold moisture. Much deeper than 4 inches can starve roots of air. Keep mulch a few inches back from tree trunks and shrub stems.
How much topsoil do I need for new sod?
Plan on about 4 inches of screened topsoil over a graded base. A 1,000 sq ft lawn at 4 inches needs about 333 cubic feet, roughly 12.3 cubic yards, before settling. Grade first so the soil falls away from the house, then roll it lightly before laying sod.
How many bags are in a cubic yard?
One cubic yard is 27 cubic feet, so it equals about thirteen 2 cu ft bags of mulch, eighteen 1.5 cu ft bags or about thirty 25 L bags. For more than about two cubic yards, bulk delivery usually costs less and saves a lot of trips and plastic.