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Raised beds swallow more soil than you’d expect — a single 8 × 4 ft bed 12 in deep takes about 1.2 cubic yards, and closer to 1.4 once you top it up after settling. Enter your bed or area below to get the volume in cubic feet and yards, the number of bags, and an estimate of the weight so you know whether it fits in your truck.
The formula
Volume = length × width × depth (all in feet), giving cubic feet. Divide by 27 for cubic yards. For round beds use π × radius² × depth. New raised beds settle by 10–20% over the first season, so the calculator can add 15% to compensate.
Soil for common raised bed sizes
| Bed size | Depth | Cubic feet | Cubic yards | 1.5 cu ft bags |
|---|---|---|---|---|
| 4 × 4 ft | 12 in | 16 | 0.59 | 11 |
| 4 × 8 ft | 12 in | 32 | 1.19 | 22 |
| 4 × 8 ft | 18 in | 48 | 1.78 | 32 |
| 3 × 6 ft | 12 in | 18 | 0.67 | 12 |
| 2 × 8 ft | 10 in | 13.3 | 0.49 | 9 |
(Before adding 15% for settling.)
Recommended depths
| Use | Depth |
|---|---|
| Lettuce, herbs, shallow-rooted crops | 6–8 in (15–20 cm) |
| Most vegetables | 10–12 in (25–30 cm) |
| Tomatoes, root crops, perennials | 18–24 in (45–60 cm) |
| Wood mulch on beds | 2–3 in (5–7.5 cm) |
| Gravel paths | 3–4 in (7.5–10 cm) over landscape fabric |
FAQ
Is bulk soil cheaper than bags?
Usually, once you need more than about one cubic yard (18 bags of 1.5 cu ft). Factor in the delivery fee and whether you can move it from the driveway.
How can I fill a tall raised bed more cheaply?
Fill the bottom third with logs, branches and leaves (hügelkultur style) and top with good soil. Expect extra settling as the wood breaks down.
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