🍂 Mulch Calculator
Enter your garden bed area and the mulch depth you want to calculate how much mulch to buy in cubic yards and standard bags.
What this calculator does
The Mulch Calculator estimates the volume of mulch needed to cover a garden bed at a chosen depth, giving results in cubic yards (how bulk mulch is usually sold) and in standard bag sizes.
How the formula works
Volume is simply area × depth, with the depth converted from inches to feet first: cubic feet = area (sq ft) × (depth in inches ÷ 12). Since bulk mulch is typically sold by the cubic yard, the cubic foot total is divided by 27 (there are 27 cubic feet in a cubic yard) to get cubic yards, and also divided by common bag sizes of 2 or 3 cubic feet.
- A 2-3 inch mulch layer is typical for most garden beds
- Thicker layers (4+ inches) can help more with weed suppression but risk smothering shallow roots if piled against stems
A note on accuracy
Bag sizes and bulk mulch pricing vary by supplier and mulch type (wood chips, bark, straw, etc.), so use this as a shopping estimate and round up slightly to account for settling and uneven bed depth.