Raised Bed Soil Calculator
Calculate the exact amount of soil needed for raised garden beds.
Supports rectangular, L-shaped, and multiple bed configurations.
Raised bed soil volume calculation ensures you buy the right amount of growing mix to fill your bed without wasting money on excess material or having too little to plant in.
The Formula:
Volume (cubic feet) = Length (ft) × Width (ft) × Depth (ft)
Volume (cubic yards) = Volume (cubic feet) / 27
Volume (liters) = Length (m) × Width (m) × Depth (m) × 1000
Standard Raised Bed Depths:
| Crop Type | Recommended Depth |
|---|---|
| Herbs, lettuce, spinach | 15 cm (6 in) |
| Tomatoes, peppers, squash | 30 cm (12 in) |
| Carrots, beets, parsnips | 45 cm (18 in) |
| Asparagus, deep-root perennials | 60 cm (24 in) |
Worked Example:
Raised bed: 4 ft wide × 8 ft long × 12 inches (1 ft) deep
Volume = 4 × 8 × 1 = 32 cubic feet
32 / 27 = 1.19 cubic yards of soil needed
At $45 per cubic yard: total cost ≈ $53.55
Mel’s Mix (Square Foot Gardening blend):
- 1/3 blended compost
- 1/3 peat moss (or coco coir)
- 1/3 coarse vermiculite
For 32 cubic feet: approximately 10.7 cubic feet of each component.
Bag Size Reference:
Most bagged potting mix comes in 1 or 2 cubic foot bags:
- 32 cubic feet ÷ 2 = 16 bags of 2 cu ft mix
Practical Tips:
- Soil settles 10–20% after watering — slightly overfill when first planting
- Never use straight topsoil in raised beds — it compacts and drains poorly
- Add compost each season to replenish nutrients and maintain structure
- If building directly over lawn, lay cardboard underneath to smother grass