Mulch Calculator
Measure your garden beds and find out how many bags or cubic yards of mulch to buy.
How much mulch do I need?
Cubic feet = Length (ft) × Width (ft) × Depth (in) ÷ 12
Divide cubic feet by 27 for cubic yards, or by the bag size for the number of bags. A 20 × 4 ft bed at 3 inches deep needs 20 cubic feet — ten 2 cu ft bags, or about 0.74 cubic yards.
For a round bed, measure the diameter and use the square footage calculator to get the area, then multiply by the depth in inches and divide by 12.
How deep should mulch be?
- Most flower and shrub beds: 2 – 3 inches
- Refreshing last year's mulch: about 1 inch on top
- Weed-heavy areas or paths: 3 – 4 inches
Keep mulch a few inches away from tree trunks and plant stems. Piling it against the bark ("mulch volcanoes") traps moisture and can cause rot.
Bags vs. bulk
One cubic yard equals 13.5 bags of 2 cubic feet. Bulk mulch is usually cheaper once you need more than 2 or 3 yards, while bags are easier for small beds and cars without a trailer.
Frequently asked questions
How much area does a bag of mulch cover?
A 2 cu ft bag covers about 12 sq ft at 2 inches deep, or 8 sq ft at 3 inches.
How much area does a cubic yard cover?
About 162 sq ft at 2 inches, 108 sq ft at 3 inches and 81 sq ft at 4 inches.
Last reviewed November 14, 2026.
