Mulch Calculator
Calculate how many cubic yards or bags of mulch you need for your garden beds.
How to use this tool
- Enter the garden bed length and width in feet.
- Choose mulch depth in inches (2–4 in is typical).
- The result shows cubic yards needed and equivalent number of 2 cu ft bags.
Calculate the amount of mulch needed for any garden bed or landscape area.
Formula
Volume (ft³) = Length (ft) × Width (ft) × Depth (in) ÷ 12
Cubic yards = Volume (ft³) ÷ 27
2 cu ft bags = ⌈Volume (ft³) ÷ 2⌉
How it works
The calculator converts a rectangular garden bed's dimensions to cubic feet by converting the depth from inches to feet, then divides by 27 to obtain cubic yards for bulk orders. Bags are counted by dividing total cubic feet by 2 (the volume of a standard 2 cu ft bag of mulch) and rounding up to the nearest whole bag. Results assume a uniform rectangular bed; irregularly shaped beds should be broken into rectangles and summed.
Worked example
Worked example
- Bed: 20 ft long × 5 ft wide, 3 in deep.
- Volume (ft³) = 20 × 5 × (3 ÷ 12) = 20 × 5 × 0.25 = 25 ft³.
- Cubic yards = 25 ÷ 27 ≈ 0.926 yd³.
- Bags (2 cu ft) = ⌈25 ÷ 2⌉ = ⌈12.5⌉ = 13 bags.
Cubic yards ≈ 0.926 yd³; 2 cu ft bags needed = 13.
Key terms
- Mulch
- Organic or inorganic material spread over soil to retain moisture, suppress weeds, and regulate temperature; common types include wood chips, bark, and straw.
- Cubic yard (yd³)
- Standard bulk purchase unit for landscape materials; equal to 27 cubic feet.
- Coverage depth
- Recommended mulch layer thickness: 2–3 in for established beds, up to 4 in for weed suppression.
- 2 cu ft bag
- A common retail bag size for bagged mulch, containing 2 cubic feet of material.
- Ceiling rounding
- Rounding up to the next whole number to ensure you buy enough bags; always used for discrete item counts.
Frequently asked questions
- How much mulch do I need?
- Multiply the bed area (ft²) by depth (in inches ÷ 12) to get cubic feet. Divide by 27 for cubic yards. A standard bag holds 2 cubic feet.
- How deep should mulch be?
- Apply 2–3 inches for most garden beds. Avoid piling mulch against plant stems (volcano mulching), which can cause rot.