Mulch Calculator
Calculate how many cubic yards or bags of mulch you need for a garden bed.
About the Mulch Calculator
Mulch is sold by the cubic yard in bulk or by the bag for smaller projects, and getting the depth right — typically 2 to 4 inches for most garden beds — matters for weed suppression and moisture retention. This calculator converts your bed dimensions and desired depth into the volume needed.
How It Works
The calculator multiplies bed length by width by depth (converted from inches to feet) to get cubic feet, then divides by 27 to convert to cubic yards, the standard bulk mulch unit. It also converts that figure into a count of standard 2-cubic-foot bags for smaller purchases.
Cubic Yards = (Length × Width × Depth(in)/12) / 27; Bags (2 cu ft each) = Cubic Feet / 2.
Example
Scenario: A 20ft × 5ft garden bed with 3 inches of mulch depth.
Result: About 0.93 cubic yards needed, or roughly 14 standard 2-cubic-foot bags.
Assumptions & Limitations
- Assumes a consistent, level mulch depth across the entire bed area.
- Bag size assumption of 2 cubic feet is standard for most retail mulch bags, though some brands package differently.
- Irregularly shaped beds should be broken into simpler rectangular sections and totaled for the most accurate volume estimate.