Raised Bed Soil Calculator
Calculate soil for one or more raised garden beds in cubic feet, yards and bags.
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What this tool does
This calculator finds the soil volume to fill raised garden beds, in cubic feet, cubic yards and bags, and splits it into a common 60/30/10 topsoil-compost-aeration mix.
How to use the Raised Bed Soil Calculator
- Enter the inside length and width of the bed.
- Enter the soil depth (usually the bed height).
- Enter the number of identical beds.
- Choose the bag size.
- Buy the bags or bulk yards shown.
Formula
cu ft = L × W × (H ÷ 12) × beds; bags = ⌈cu ft ÷ bag⌉
- L, W
- Inside dimensions (ft)
- H
- Soil depth (in)
- bag
- Bag size (cu ft)
Worked example
One 8 × 4 ft bed, 12 inches deep, using 1.5 cu ft bags.
Inputs
- Bed length8 ft
- Bed width4 ft
- Bed height (soil depth)12 in
- Number of beds1
- Bag size1.5 cu ft
Result
- Soil needed32 cu ft
- Cubic yards1.19 cu yd
- Bags (1.5 cu ft)22
- Suggested mix: topsoil 60%19.2 cu ft
- Suggested mix: compost 30%9.6 cu ft
- Suggested mix: aeration 10%3.2 cu ft
Soil for common raised bed sizes (cu ft)
| Bed | 6 in | 12 in | 18 in |
|---|---|---|---|
| 4 × 4 ft | 8 | 16 | 24 |
| 4 × 8 ft | 16 | 32 | 48 |
| 3 × 6 ft | 9 | 18 | 27 |
| 2 × 8 ft | 8 | 16 | 24 |
| 4 × 12 ft | 24 | 48 | 72 |
Results explained
- Soil needed
- Total cubic feet across all beds.
- Cubic yards
- For bulk delivery.
- Bags
- Whole bags to buy.
- Mix components
- Volume of each part of a 60/30/10 blend.
Frequently asked questions
At 12 in deep, 32 cubic feet (about 1.2 cubic yards or 22 bags of 1.5 cu ft).
A common blend is 60% topsoil, 30% compost and 10% aeration (perlite or pumice).
In tall beds, logs and branches (hugelkultur) can fill the bottom third to save soil.
12 inches suits most vegetables; 18–24 inches for root crops or poor native soil.
Expect 10–20% settling in the first season; top up with compost.