Raised Garden Bed Calculator
Enter your bed dimensions and fill mix to find out exactly how much soil you need — plus cubic feet, bags, and estimated cost.
Bed Dimensions
Fill Mix
How Deep Should a Raised Bed Be?
| Depth | Best For | Notes |
|---|---|---|
| 6 inches | Herbs, lettuce, spinach, flowers | Minimum depth — works for shallow-rooted crops only |
| 8–10 inches | Most vegetables — tomatoes, peppers, beans | Good all-purpose depth for most home gardens |
| 12 inches | All vegetables | Most recommended depth — comfortable root space for everything |
| 18–24 inches | Root vegetables — carrots, parsnips, potatoes | Required for deep-rooted crops; also needed over concrete or hardscape |
Soil Volume Quick Reference
| Bed Size | 6" Deep | 12" Deep | 18" Deep |
|---|---|---|---|
| 4×4 ft | 8 cu ft (6 bags) | 16 cu ft (11 bags) | 24 cu ft (16 bags) |
| 4×8 ft | 16 cu ft (11 bags) | 32 cu ft (22 bags) | 48 cu ft (32 bags) |
| 4×12 ft | 24 cu ft (16 bags) | 48 cu ft (32 bags) | 72 cu ft (48 bags) |
| 3×6 ft | 9 cu ft (6 bags) | 18 cu ft (12 bags) | 27 cu ft (18 bags) |
| 5×10 ft | 25 cu ft (17 bags) | 50 cu ft (34 bags) | 75 cu ft (50 bags) |
Bag count assumes standard 1.5 cu ft bags. Actual bag sizes vary — check the label. For large beds, bulk delivery by the cubic yard is usually cheaper above 3–4 cubic yards.
Fill Type Comparison (2026)
| Fill Type | Cost per Cu Ft | Best For | Notes |
|---|---|---|---|
| Pre-mixed raised bed soil (bagged) | $5–$9 | Small beds, convenience | Ready to use, consistent quality |
| Mel's Mix (⅓ compost / ⅓ peat / ⅓ vermiculite) | $6–$10 | Best plant performance | Lightweight, excellent drainage, retains moisture |
| Topsoil + compost 60/40 | $3–$6 | Budget option, larger beds | Heavier, may compact over time |
| Bulk garden mix | $35–$55/cu yd ($1.30–$2/cu ft) | Large beds, multiple beds | Cheapest per cu ft above 3 cu yd |