Mulch Calculator
Calculate how much mulch you need in cubic yards and 2 cubic foot bags to cover a garden bed at your chosen depth.
How it works
Mulch volume formula
Volume (ft³) = Length (ft) × Width (ft) × Depth (ft) Cubic yards = ft³ ÷ 27 Bags = ft³ ÷ 2 (for 2 ft³ bags)
Mulch is applied at a chosen depth over a bed, so the amount needed is simply the area times the depth. Convert the depth from inches to feet (divide by 12), compute the volume, then convert to cubic yards for bulk delivery or divide by the bag size for bagged mulch.
Worked example
A 20 ft × 10 ft bed at 3 inches deep needs 20 × 10 × 0.25 = 50 ft³ = 1.85 yd³ of mulch — about 25 bags of 2 cubic foot mulch.
Frequently asked questions
How deep should mulch be?
For most garden beds, 2–3 inches is ideal — enough to suppress weeds and retain moisture without smothering roots. Refresh to that depth rather than piling new mulch on top each year.
How many bags are in a cubic yard?
A cubic yard is 27 cubic feet. With standard 2 cubic foot bags, that's about 13.5 bags. Buying in bulk by the yard is usually cheaper for large areas.
Should I order extra mulch?
Adding about 5–10% helps cover settling and uneven beds. Mulch also compresses over time, so slightly rounding up gives a better finished depth.