Raised Garden Bed Soil Calculator â How Much Soil Do I Need?
Enter your bed length, width and depth to get soil in cubic feet, cubic yards, and bags. No sign-up, no data stored.
Soil needed
How raised bed soil is calculated
- Cubic feet = length à width à (depth ÷ 12). A 4Ã8 bed at 12 in is 4 à 8 à 1 = 32 cu ft.
- Cubic yards = cubic feet ÷ 27.
- Bags = cubic feet ÷ bag size, rounded up.
- Inside measure: use the interior dimensions â a 2-in frame on all sides makes a meaningful difference on deep beds.
New soil settles 10â15% after the first watering. Either fill to the top and let it settle, or add about 10% to your volume for a self-seeded top-up later. For beds over 24 in deep, put 6â8 in of filler (logs, branches, coarse material) at the bottom â plants don't need soil that deep.
Common raised bed sizes
Soil volume for popular bed sizes at 12 in deep.
| Bed size | Cubic feet | Cubic yards | Bags (1.5 cu ft) |
|---|---|---|---|
| 2Ã4 ft | 8 | 0.3 | 6 |
| 3Ã6 ft | 18 | 0.7 | 12 |
| 4Ã4 ft | 16 | 0.6 | 11 |
| 4Ã8 ft | 32 | 1.2 | 22 |
| 4Ã12 ft | 48 | 1.8 | 32 |
Last updated: October 2026 · Volumes assume 12-in depth and don't include settling. Measure the inside of your frame before ordering.
Raised bed soil FAQ
About 32 cubic feet at 12 in deep â that's 1.2 cubic yards or 22 bags of 1.5-cu-ft soil. At 6 in deep you'd need half that: 16 cu ft (11 bags).
6 inches for shallow greens, 12 inches for most vegetables and herbs, and 18â24 in for root crops or perennials. Deeper beds also hold moisture better in hot climates.
Divide cubic feet by the bag size and round up. A 32-cu-ft bed takes 22 bags of 1.5-cu-ft soil, or 16 bags of 2-cu-ft soil. Bags of 1.5 and 2 cu ft are the common retail sizes.
For beds over about 1 cubic yard, bulk delivery is usually cheaper â often $30â60 per yard versus $5â8 per 1.5-cu-ft bag. For small beds, bags avoid a delivery minimum and handling.
A common blend is 60% topsoil, 30% compost and 10% aeration (perlite or coarse sand). Pre-mixed raised-bed blends work too; avoid pure compost, which settles and can burn young roots.
Related calculators & guides
How Much Topsoil Do I Need?
How much topsoil you need for a lawn or garden bed: the volume formula, cubic yards to bags, quick sizes, and a worked example. Plus a free calculator.
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