How to calculate mulch
Measure the bed at its longest and widest points. Multiply length by width for area, then multiply by mulch depth after converting every measurement to feet.
Mulch formula
Cubic feet = length × width × (depth in inches ÷ 12). Divide cubic feet by 27 for cubic yards. Bag estimates round up to whole bags.
Worked example
A 20 × 10 foot bed covered 3 inches deep needs 50 cubic feet, or about 1.85 cubic yards. That equals 25 two-cubic-foot bags or 17 three-cubic-foot bags.
Practical tips
- Two to three inches is common for many landscape beds; follow guidance for your mulch and plants.
- Split curved beds into smaller rectangles and add their volumes.
- Allow for settling and uneven ground, but avoid piling mulch against trunks or foundations.
Assumptions and limitations
The result assumes a rectangular area and uniform depth. Bag coverage and settling vary, so confirm the volume printed on the product.
Frequently asked questions
How many bags are in a cubic yard?
One cubic yard equals 27 cubic feet: about fourteen 2-cubic-foot bags or nine 3-cubic-foot bags when rounded up.
Should I remove old mulch?
Measure the depth still present and apply only enough new material to reach the desired total depth.