How to calculate soil for raised beds
Cubic yards = Cubic feet ÷ 27
Example: a 4 ft × 8 ft bed filled 12 inches deep holds 32 cubic feet. With 10% extra for settling that's about 35 cubic feet — 35 bags of 1 cu ft, or 1.3 cubic yards.
How deep should a raised bed be?
| Plants | Soil depth |
|---|---|
| Lettuce, herbs, strawberries | 6–8 in |
| Most vegetables and flowers | 10–12 in |
| Tomatoes, potatoes, carrots, root crops | 12–18 in |
What soil to use
A popular recipe is roughly 60% screened topsoil and 40% compost, or a bagged raised-bed mix. Avoid using only compost or only topsoil. Soil settles 10–20% in the first season, so top up with compost each spring.
Tall bed? You can fill the bottom with logs, branches or leaves to save soil, as long as the top 12 inches is good soil.
Frequently asked questions
How much soil do I need for a 4×8 raised bed?
32 cubic feet at 12 inches deep (about 1.2 cubic yards), or 21 cubic feet at 8 inches.
How many bags of soil for a raised bed?
For a 4×8×1 ft bed, about 32 bags of 1 cu ft or 16 bags of 2 cu ft, plus 10% for settling.
How many cubic feet are in a yard of soil?
27 cubic feet.
Should I put rocks at the bottom of a raised bed?
No — rocks don't improve drainage. Use good soil, or fill the base with organic material like logs and leaves.
Related calculators
These figures are estimates for planning only. Material weights and coverage vary by supplier, moisture and compaction. Always confirm quantities and prices with your supplier before ordering. See our terms & disclaimer.