Mulch Calculator
Estimates mulch volume in cubic metres needed to cover a garden bed.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the length, width and depth.
- Press Calculate.
How it works
Volume = length × width × depth — the cubic metres of mulch to order.
Worked example
5 × 4 × 0.05 m. = 1 m³.
Common mistakes
- Spreading mulch thick against stems, which can rot plants — keep it clear of trunks.
- Forgetting mulch settles and breaks down, so top-ups are needed over time.
Frequently asked questions
How much mulch do I need?
Area × depth gives the volume. A 25 m² bed at 75 mm deep needs about 1.9 m³ of mulch.
How thick should mulch be?
About 50–75 mm suppresses weeds and holds moisture without smothering plants; keep it pulled back from trunks and stems.
How thick should I spread mulch?
Usually 50–75 mm — deep enough to suppress weeds and hold moisture, without smothering plant stems and roots.
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Cite this tool
Zerdly. (2026). Mulch Calculator. Retrieved from https://www.zerdly.com/tools/mulch-calculator/
Tip: Enter any known values to calculate the remaining results.
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