The formula
How the volume is calculated
Multiply 4 ft by 8 ft, then multiply by the soil depth converted from inches to feet. A 12-inch depth is 1 foot, so that example is 4 × 8 × 1 = 32 cubic feet.
Cubic feet = 4 × 8 × (depth in ÷ 12)
Worked example
How Much Soil Do I Need for a 4x8 Raised Bed?
A 4 ft × 8 ft raised bed needs a different amount of soil depending on how deep you fill it. Use the table for a quick buying estimate, then calculate your exact bed.
4×8 soil table
Soil volume by fill depth
Bag counts use 1.5 cu ft bags and are rounded up to the next whole bag.
| Soil depth | Cubic feet | Cubic yards | 1.5 cu ft bags |
|---|---|---|---|
| 6 in | 16 | 0.59 | 11 |
| 8 in | 21.33 | 0.79 | 15 |
| 12 in | 32 | 1.19 | 22 |
| 18 in | 48 | 1.78 | 32 |
Not sure what depth to use? Read our raised-bed depth guide →
Buying quantities
Bags or cubic yards
Bag counts are rounded up because soil is sold in whole bags. If you buy bulk soil, use the cubic-yard figure when asking a supplier for pricing and delivery terms.
Suppliers may use minimum orders or quantity increments, so confirm the final order locally.
Your measurements