How much soil for a 4×8 raised bed?
Quick Answer
A standard 4×8 foot raised bed filled 12 inches deep needs 32 cubic feet of soil — about 1.19 cubic yards. At 10 inches deep: 0.99 yd³. At 6 inches: 0.59 yd³. Most gardeners use a mix of topsoil, compost, and coarse vermiculite (Mel's Mix) rather than straight topsoil for better drainage and root development.
Quick Reference Table
| Fill depth | Soil needed for 4×8 raised bed |
|---|---|
| 6 inches | 16 cu ft / 0.59 yd³ |
| 8 inches | 21.3 cu ft / 0.79 yd³ |
| 10 inches | 26.7 cu ft / 0.99 yd³ |
| 12 inches | 32 cu ft / 1.19 yd³ |
| 16 inches | 42.7 cu ft / 1.58 yd³ |
| Bags needed (1 cu ft bags, 12") | 32 bags |
How to Calculate It Yourself
- 1
Calculate volume: 4 ft × 8 ft × depth (ft). At 12": 4 × 8 × 1 = 32 cubic feet.
- 2
Convert to cubic yards: 32 ÷ 27 = 1.19 yd³.
- 3
For Mel's Mix (recommended): ⅓ compost, ⅓ peat moss or coco coir, ⅓ coarse vermiculite.
- 4
At 12" deep, buy 11 cubic feet each of compost, peat, and vermiculite. Or order 1.2 yards of pre-blended raised bed mix.
Pro Tip
Never fill a raised bed with straight topsoil — it compacts badly and drains poorly. Blended "raised bed mix" from garden centers costs more but plants perform dramatically better. Budget $60–120 for a 4×8×12 fill with quality blended mix.
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