Raised Bed Soil Calculator
Soil volume and the number of bags for your raised garden beds.
Updated · How we check our maths
- Soil needed
- 32 cu ft
- Cubic yards
- 1.19 yd³
- Litres
- 906 L
- Bags of 1.5 cu ft (+10% for settling)
- 24
- Suggested mix
- 60% topsoil, 30% compost, 10% aeration (perlite/pumice)
Quick answer
Soil (cu ft) = length × width × depth, with depth in feet. A 4 × 8 ft bed filled 12 inches deep needs 32 cu ft (about 1.2 cubic yards) — 22 bags of 1.5 cu ft once you allow 10% for settling.
What the Raised Bed Soil Calculator does
Enter the size of your raised bed and the depth of soil. The calculator works out the volume in cubic feet, cubic yards and litres, and the number of bags to buy (with 10% extra because soil settles). For larger projects — usually over 1 cubic yard — buying in bulk by the yard is cheaper than bags.
The formula
Volume = L × W × (depth in inches ÷ 12) × beds; cubic yards = cubic feet ÷ 27; bags = volume × 1.1 ÷ bag size.
Worked example
Three 3 × 6 ft beds, 10 in deep: 3 × 6 × 0.833 × 3 = 45 cu ft = 1.67 yd³.
How to use the Raised Bed Soil Calculator
- Enter the inside length and width of the bed.
- Enter the soil depth in inches.
- Set the number of beds and your bag size.
Frequently asked questions
How deep should a raised bed be?
8–12 inches suits most vegetables; root crops like carrots prefer 12–18 inches.
What soil mix is best for raised beds?
A common mix is about 60% topsoil, 30% compost and 10% perlite or pumice.
Should I fill the bottom with something else?
In deep beds, logs and branches (hügelkultur) can reduce the soil you need, but they settle over time.
Results are estimates for planning and learning. Check important figures with a qualified professional. How we build and check our calculators.