By Azura · Updated June 2026 · Raised Garden Hub is reader-supported. When you buy through links on our site, we may earn an affiliate commission at no extra cost to you.
A 4×8 ft raised bed needs 32 cubic feet of soil at 12 inches deep — about 21 bags (1.5 cu ft each), or 1.2 cubic yards. Here are the exact numbers for every common depth, plus how to fill it for less.
4x8 raised bed soil by depth
| Depth | Cubic feet | Cubic yards | Bags (1.5 cu ft) |
|---|---|---|---|
| 6 in | 16 | 0.6 | ~11 |
| 10 in | 27 | 1.0 | ~18 |
| 12 in | 32 | 1.2 | ~21 |
| 18 in | 48 | 1.8 | ~32 |
Buy about 10% extra for settling. Soil drops a few inches in the first season.
The math (so you can do any size)
Soil volume = length × width × depth, all in feet. Depth is usually in inches, so divide by 12
first. For a 4×8 bed at 12 inches: 4 × 8 × (12 ÷ 12) = 32 cubic feet.
Want it done automatically for any bed? Use our soil calculator — it gives cubic feet, bags, and a Mel’s Mix recipe instantly.
Fill it cheaper
You don’t need premium mix all the way down — roots live in the top 8–12 inches. For a deep 18” bed, fill the bottom third with logs, branches, and leaves (the hugelkultur method) and save the good soil mix for the top. That cuts the bill by roughly a third.
Next steps
- Not sure how deep to go? See how deep a raised bed should be.
- Choosing a bed? See the best raised garden beds of 2026.
Frequently asked questions
How much soil for a 4x8 raised bed that's 12 inches deep?
32 cubic feet (1.2 cubic yards), which is about 21 bags of 1.5 cubic foot soil. Buy ~10% extra for settling.
How much soil for a 4x8 raised bed that's 6 inches deep?
16 cubic feet (about 11 bags of 1.5 cubic feet). A 6-inch bed suits greens and herbs.
How many bags of soil for a 4x8 raised bed?
About 21 bags (1.5 cu ft each) for a 12-inch-deep bed, or 11 bags for a 6-inch bed. Using 2 cu ft bags, that's roughly 16 and 8 bags.
How can I fill a 4x8 bed cheaper?
Fill the bottom third with logs, branches, and leaves (hugelkultur), then only buy quality mix for the top 8–12 inches. This cuts soil cost by about a third on a deep bed.