Enter your bed size and soil depth to see how much soil you need in cubic feet, cubic yards, litres and bags. Switch to metric if you measure in metres and centimetres.
Raised Bed Soil Calculator
Estimates only. Check with your supplier before you order, and always buy a little extra.
How much soil does a raised bed need?
Multiply the length by the width by the depth. Because depth is usually measured in inches, divide it by 12 first to turn it into feet:
Soil (cubic feet) = length (ft) × width (ft) × depth (in) ÷ 12
Divide cubic feet by 27 to get cubic yards, which is how bulk soil is usually sold in the US. To count bags, divide cubic feet by the bag size and round up.
Example: a 4 × 8 ft bed, 12 inches deep
- 4 × 8 × 12 ÷ 12 = 32 cubic feet
- 32 ÷ 27 = about 1.2 cubic yards
- In 1.5 cu ft bags: 32 ÷ 1.5 = 21.3, so 22 bags (24 bags with 10% extra for settling)
Soil for common raised bed sizes
| Bed size | Depth | Cubic feet | Cubic yards |
|---|---|---|---|
| 4 × 4 ft | 12 in | 16 | 0.59 |
| 2 × 8 ft | 12 in | 16 | 0.59 |
| 3 × 6 ft | 12 in | 18 | 0.67 |
| 4 × 8 ft | 6 in | 16 | 0.59 |
| 4 × 8 ft | 12 in | 32 | 1.19 |
| 4 × 8 ft | 18 in | 48 | 1.78 |
Figures are before any extra for settling.
Tips before you buy
- Add extra for settling. New soil settles as it is watered, so many gardeners buy around 10% more. The calculator adds this when the box is ticked.
- Bags or bulk? Bags are easier for one or two small beds. For around a cubic yard or more, bulk delivery is often cheaper per cubic foot. Compare prices locally.
- Depth. Many vegetables and flowers grow well in 8–12 inches of soil. Deep-rooted crops such as carrots, parsnips and tomatoes appreciate more.
- Tall beds. In a very deep bed, some gardeners fill the bottom with logs, branches or other organic material to reduce how much soil they buy. If you do this, measure only the depth you will fill with soil.
- The mix. The calculator shows one common example blend (mostly topsoil with compost). There is no single right recipe; adjust it to your plants and local advice.
Frequently asked questions
How many bags of soil do I need for a 4 × 8 raised bed?
At 12 inches deep, a 4 × 8 bed holds 32 cubic feet, which is about 22 bags of 1.5 cu ft, or 32 bags of 1 cu ft. Add around 10% if you want extra for settling.
How many cubic feet are in a cubic yard?
27. A cubic yard is 3 ft × 3 ft × 3 ft.
How many litres are in a cubic foot?
About 28.3 litres.
Does the calculator work for several beds?
Yes. Enter the size of one bed and the number of beds. For beds of different sizes, work each one out and add the results together.