Soil and raised bed calculator
How much soil fills your raised beds, in cubic feet, cubic yards and bags, with room for settling.
- 1 cu ft bags
- 1.5 cu ft bags
- 2 cu ft bags
How to use it
Enter the inside length and width of the bed in feet and how deep you'll fill it in inches. If you're filling several beds the same size, enter how many. The calculator shows the soil you need in cubic feet and cubic yards, and the number of bags in each common size.
Measure the inside of the bed, not the outside. Thick timber walls can take several inches off each side.
How it's calculated
- Length × width × (depth ÷ 12) × number of beds = cubic feet.
- Add the settling allowance.
- Cubic feet ÷ 27 = cubic yards. Cubic feet ÷ bag size, rounded up = bags.
| Bed size | Depth | Soil (no extra) |
|---|---|---|
| 4 × 4 ft | 12 in | 16 cu ft |
| 4 × 8 ft | 12 in | 32 cu ft (about 1.2 cu yd) |
| 4 × 8 ft | 18 in | 48 cu ft (about 1.8 cu yd) |
| 3 × 6 ft | 12 in | 18 cu ft |
Why add extra for settling?
Fresh soil and compost are full of air. After a few waterings the level drops, often by several inches in a deep bed. Adding 10 to 20% up front saves a second trip. The calculator starts at 10%; set it to 0 if you plan to top up later.
Filling deep beds for less
Beds deeper than about 12 inches use a lot of soil. A common approach is to fill the bottom with logs, branches or coarse organic material, then add soil on top. If you do, measure the depth of soil you'll actually add rather than the full height of the bed.
Bags or bulk?
Bagged soil is convenient for a bed or two. For several beds, bulk soil or a soil and compost blend sold by the cubic yard usually costs much less. One cubic yard equals 27 one-cubic-foot bags.