Mulch Bags for 10x10, 10x20 & 20x20 Beds
Quick answers: at 3 in deep, a 10x10 bed needs 13 bags of 2 cu ft mulch, a 10x20 needs 25, and a 20x20 needs 50 (about 3.7 yd³, which is worth buying bulk).
Bag counts by bed size and depth
| Bed | Depth | Cu yd | 2 cu ft bags | 3 cu ft bags |
|---|---|---|---|---|
| 10 × 10 ft | 2 in | 0.62 | 9 | 6 |
| 10 × 10 ft | 3 in | 0.93 | 13 | 9 |
| 10 × 10 ft | 4 in | 1.23 | 17 | 12 |
| 10 × 20 ft | 2 in | 1.23 | 17 | 12 |
| 10 × 20 ft | 3 in | 1.85 | 25 | 17 |
| 10 × 20 ft | 4 in | 2.47 | 34 | 23 |
| 20 × 20 ft | 2 in | 2.47 | 34 | 23 |
| 20 × 20 ft | 3 in | 3.7 | 50 | 34 |
| 20 × 20 ft | 4 in | 4.94 | 67 | 45 |
| 5 × 10 ft | 2 in | 0.31 | 5 | 3 |
| 5 × 10 ft | 3 in | 0.46 | 7 | 5 |
| 5 × 10 ft | 4 in | 0.62 | 9 | 6 |
| 4 × 8 ft | 2 in | 0.2 | 3 | 2 |
| 4 × 8 ft | 3 in | 0.3 | 4 | 3 |
| 4 × 8 ft | 4 in | 0.4 | 6 | 4 |
| 3 × 30 ft | 2 in | 0.56 | 8 | 5 |
| 3 × 30 ft | 3 in | 0.83 | 12 | 8 |
| 3 × 30 ft | 4 in | 1.11 | 15 | 10 |
Odd-shaped beds
- Circle: area = 3.14 × radius². A 10 ft diameter tree ring is 78.5 sq ft.
- Triangle: area = ½ × base × height.
- Curvy beds: break them into rectangles and circles, add the areas, and enter the total in the main mulch calculator.
A tip from experience: buy a few bags fewer than the count, finish the visible front edge first, and go back for more. Bags are easy to buy and hard to return once they're wet.
Frequently asked questions
How many bags of mulch for a 10x10 area?
At 3 in deep, 13 bags of 2 cu ft (25 cu ft). At 2 in, 9 bags.
How many bags of mulch for a 10x20 bed?
At 3 in deep, 25 bags of 2 cu ft, or 17 bags of 3 cu ft.
How much mulch for a 20x20 area?
At 3 in deep, 100 cu ft = 3.7 yd³ = 50 bags of 2 cu ft. Bulk is usually cheaper at that size.
Last reviewed October 2026 by Jim Frith. These are planning estimates; confirm quantities with your supplier and follow local codes.