How much mulch for a 20 x 20 bed?
Short answer
- A 20 x 20 ft bed is 400 square feet. At 3 inches deep it needs 3.7 cubic yards (100 cubic feet) of mulch.
- With 5% extra: 53 bags of 2 cu ft or 35 bags of 3 cu ft (3.89 cubic yards).
- It's typically a play area or a large island bed.
- If you edge all four sides, that's 80 feet of edging.
Mulch for a 20 x 20 bed at 2, 3, 4 inches
Cubic yards are shown without extra so you can compare quotes. The other columns include 5% extra.
Open this bed in the mulch calculator to change the size, depth, extra or material.
How the math works
20 ft × 20 ft = 400 sq ft. At 3 inches deep that's 400 × 3 ÷ 12 = 100 cubic feet, and ÷ 27 = 3.7 cubic yards. Adding 5% gives 105 cubic feet to buy.
How deep should it be?
Penn State Extension recommends a 2 to 4 inch layer of mulch. Use the low end for fine shredded mulch or to top up an old layer, and keep mulch a few inches away from tree trunks and stems.
Other sizes
- 3 x 30 bed90 sq ft, typically a long border along a fence or walk.
- 10 x 10 bed100 sq ft, typically a corner bed or an island bed.
- 10 x 20 bed200 sq ft, typically a large planting bed.
- 10 x 50 bed500 sq ft, typically a long property-line border.
- 30 x 30 bed900 sq ft, typically a big play area or a whole side yard.