Mulch Calculator
Find out exactly how much mulch your garden beds need — in cubic yards, bags, and dollars.
Results are estimates for planning. Mulch settles and coverage varies by material and grind. Order a little extra for topping up thin spots.
How to Measure for Mulch
Mulch coverage depends on two things: the area you're covering and how deep you spread it. Length and width go in feet; depth goes in inches.
Rectangular beds
Measure the length and width of the bed in feet and use the Length × Width tab. For an L-shaped bed, split it into rectangles and add each result.
Irregular or curved beds
Estimate the total square footage — pace it out or use a garden hose to outline the shape — and use the Total area tab.
Choosing a depth
Use 2-3 inches around established plants and 3-4 inches where you want to suppress weeds. Going deeper than 4 inches wastes mulch and can harm roots.
Common Mistakes to Avoid
- Mulch volcanoes. Piling mulch against tree trunks or plant stems traps moisture and invites rot. Keep a few inches clear.
- Going too deep. More than 4 inches suffocates roots and sheds water instead of absorbing it.
- Forgetting settling. Fresh mulch compacts over a few weeks — spread slightly proud of your target depth.
- Measuring only the straight edges. Curved beds are easy to underestimate; use the total-area method when in doubt.
Frequently Asked Questions
Multiply the bed area in square feet by the depth in feet, then divide by 27 for cubic yards. A 200 sq ft bed at 3 inches deep needs about 50 cubic feet, or 1.85 cubic yards.
Use 2-3 inches around plants and flower beds, and 3-4 inches for general ground cover or weed suppression. Avoid going deeper than 4 inches.
A standard bag holds 2 cubic feet. A cubic yard is 27 cubic feet, so it takes 13.5 bags to equal one cubic yard.
Bulk mulch is usually cheaper per unit and makes sense beyond about 1.5 cubic yards. Bagged mulch is more convenient for small beds and easier to transport.
Late spring, once the soil has warmed, is ideal. A top-up in autumn insulates roots over winter. Refresh mulch yearly as it breaks down.