Planter Box Soil Calculator
Calculate the volume of soil needed to fill a planter box, raised bed, or container garden based on dimensions.
Soil Needed
Planter box soil volume is calculated from the interior dimensions.
Volume = Length × Width × Depth
Unit conversions:
- 1 cubic foot = 7.48 gallons = 25.7 dry quarts
- 1 cubic yard = 27 cubic feet
- 1 bag of potting soil = typically 1–2 cubic feet
Common planter sizes and soil needed:
| Planter | Soil Needed |
|---|---|
| Window box (36×6×6") | 0.75 cu ft |
| Small raised bed (4×2×1') | 8 cu ft |
| Medium raised bed (4×4×1') | 16 cu ft |
| Large raised bed (4×8×1') | 32 cu ft |
Cost tip: For raised beds deeper than 12 inches, fill the bottom 1/3 with logs, branches, or straw (hugelkultur method) to save on soil and improve drainage.
Soil mix for containers:
- Potting soil: 60%
- Compost: 30%
- Perlite: 10%