How Much Mulch Do I Need? Real Numbers for Every Garden Bed Size

Most homeowners need a quick answer, not a master class in volume math. Here are the most common garden bed sizes worked out — pick the one closest to yours and round up.

4-foot tree ring at 3 inches deep

Area = 12.6 sq ft. Volume = 3.1 cu ft, or 0.12 cubic yards. About 2 bags of 2-cu-ft mulch. One bag if you stretch coverage.

10 × 4 foundation bed at 3 inches

40 sq ft × 0.25 ft = 10 cu ft = 0.37 yd³. Five bags, or about 0.5 yd³ bulk. Bags win on price for a job this small.

20 × 6 front-of-house bed at 3 inches

120 sq ft × 0.25 ft = 30 cu ft = 1.11 yd³. 15 bags, or one cubic yard bulk. This is the breakeven point — compare delivery fees carefully.

40 × 6 side-yard border at 3 inches

240 sq ft × 0.25 ft = 60 cu ft = 2.22 yd³. 30 bags, or 2.5 cubic yards bulk. Bulk wins by ~30% at this size.

Whole front yard re-mulch: 600 sq ft at 3 inches

150 cu ft = 5.56 yd³. 75 bags is a back-breaker — order 6 cubic yards bulk and save $200.

Backyard 1,200 sq ft at 3 inches

300 cu ft = 11.1 yd³. Definitely bulk. Expect 1–2 truckloads. Plan a tarp landing zone in the driveway.

Quick reference: bags per cubic yard

• 13.5 bags per yard if buying 2-cu-ft bags
• 18 bags per yard for 1.5-cu-ft bags
• 9 bags per yard for 3-cu-ft bags

Quick reference: square feet per cubic yard at common depths

• 2" depth → 162 sq ft per yard
• 3" depth → 108 sq ft per yard
• 4" depth → 81 sq ft per yard
• 6" depth → 54 sq ft per yard

Add 10% — always

Beds settle, edges are uneven, and you'll find one more strip to cover. Order 10% over your calculated number for any job above one yard. For bag jobs, just round up to the next bag.