Mulch Calculator
Mulch in cubic yards or bags for a bed of a given area and depth.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Volume = Length × Width × Depth
Weight = Volume × bulk density
Run the calculation to see each step with your own numbers.
A 40 ft × 8 ft bed, 3 in of mulch, 5% waste.
Volume = 80 ft³ = 2.96 yd³ exact → order 3.11 yd³
≈ 40 bags of 2 ft³, or a 3-yard bulk delivery
- Rectangular bed of uniform depth.
- Bulk-mulch density varies enormously with type and moisture (400–1000 lb/yd³) — the weight is a rough guide only; order by volume.
- Bagged mulch is commonly 2 ft³ per bag — 1 yd³ ≈ 13.5 bags.
- How many bags in a cubic yard?
- About 13.5 bags of the common 2 ft³ size (27 ft³ ÷ 2). Bulk delivery is usually cheaper above ~2 yd³ once you factor in handling.
- Why is the weight so uncertain?
- Fresh, wet hardwood mulch can weigh twice what dry pine-bark mulch does. Order mulch by volume, not weight.
Volume
Standard geometry: Volume = L × W × D. Unit conversions per NIST SP 811.
Bulk density
Bulk wood/bark mulch ≈ 400–550 kg/m³ green (≈700–1000 lb/yd³). Composting Council / landscape-supply figures. Very moisture-dependent.
About the Mulch Calculator
The Mulch Calculator converts a bed area and depth into cubic yards of bulk mulch and the equivalent number of bagged units. Mulch weight varies enormously with type and moisture, so order by volume, not weight. Use 2–3 inches on an established bed and 3–4 on a new one; bulk delivery usually beats bags above about two cubic yards.
What you enter
- Length
- Width
- Depth — 2–3 in for an established bed; 3–4 in for a new bed or heavy weed pressure.
- Waste allowance — Default 5%. Adjust to your own allowance — the exact figure is always shown too.
What you get back
- Mulch volume — shown as the exact figure and, separately, a recommended figure with your waste allowance added.
- Approx. weight — Suppliers usually sell by weight. Weight uses the material's bulk density (adjustable).
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
Related calculators
- Landscape Rock Calculator — Decorative rock by volume and weight for a landscaped bed.
- Cubic Yard Calculator — Convert a length, width and depth into cubic yards, cubic feet or cubic metres.
- Gravel Calculator — Gravel by volume and by delivered weight for driveways, paths and fill.
Part of the Landscaping & Driveway calculators.