How the raised bed calculator works
Actual height of lumber beds
Lumber is smaller than its name. If you build with boards on edge, use the real height:
| Board | Actual height | Two boards stacked |
|---|---|---|
| 2×6 | 5.5 in | 11 in |
| 2×8 | 7.25 in | 14.5 in |
| 2×10 | 9.25 in | 18.5 in |
| 2×12 | 11.25 in | 22.5 in |
What soil should go in a raised bed?
Plain garden soil compacts in a bed. Most gardeners use a blend of screened topsoil and compost, or a bagged raised-bed mix. Many people fill tall beds partly with logs, branches and leaves at the bottom to save soil — if you do, subtract that depth before calculating.
Bags or bulk?
A cubic yard is 27 cubic feet — that's 18 bags of 1.5 cu ft. Once you need more than about a yard, bulk soil from a landscape supplier usually costs much less than bags.
Frequently asked questions
How much soil for a 4x8 raised bed?
A 4×8 bed filled 12 inches deep holds 32 cubic feet (1.19 cubic yards) — 22 bags of 1.5 cu ft.
How deep should a raised bed be?
6–8 inches works for lettuce and herbs, 10–12 inches suits most vegetables, and 18–24 inches is good for root crops and easier on your back.
How many bags of soil in a yard?
27 bags of 1 cu ft, 18 bags of 1.5 cu ft, or 13.5 bags of 2 cu ft.