Mulch Calculator
Work out how much mulch you need to cover a garden bed to a given depth.
Mulch by volume
Mulch is spread to a depth over an area, so the amount you need is a volume — the area times the depth. This works out that volume from your bed's size and the depth you want, so you can order the right amount of mulch rather than guessing by the bag.
Enter the area and depth to see the mulch required.
Getting the depth right
Depth is where mulching goes wrong in both directions. Too thin and it fails at its main jobs — suppressing weeds and holding moisture in the soil — so a decent layer, typically a few inches, is needed to work. Too thick, piled up against plant stems and tree trunks, and it can hold damp against them and cause rot, the classic mistake of mulch volcanoes around trees. So the right depth matters for the plants, not just the quantity.
Mulch Calculator FAQ
How deep should mulch be?
Typically a few inches — thin enough not to smother, thick enough to suppress weeds and hold moisture. Keep it off plant stems and trunks.
Why not pile mulch against tree trunks?
Because it holds damp against the bark and can cause rot — the common mistake of mulch mounded up around trees.
Is anything uploaded?
No. The calculation happens in your browser.