| Shape | Length / Diameter | Width | Height | Quantity | Actions |
|---|
Common raised bed scenarios. Volumes include the settling allowance shown in Global Settings.
| Scenario | Shape | Dimensions | Height | Qty | Volume (ft³) | Volume (yd³) | Volume (L) |
|---|
Formula Used
Rectangular bed: V = L × W × H, where L is inside length, W is inside width, and H is soil depth (all in the same units). For multiple identical beds, multiply by quantity.
Round (cylindrical) bed: V = π × (D/2)² × H, where D is inside diameter and H is soil depth. For multiple identical beds, multiply by quantity.
Settling allowance: Vfinal = V × (1 + s/100), where s is the top-up percentage to compensate for settling after watering and time.
Conversions: 1 yd³ = 27 ft³, 1 m³ ≈ 35.3147 ft³, 1 ft³ ≈ 28.3168 L.
How to Use This Calculator
- Choose your input units for all bed dimensions.
- Set a settling allowance if you plan to top-up later.
- Enter each bed on its own row. Pick the shape.
- Provide inside dimensions: length and width for boxes, diameter for round beds.
- Enter soil depth (height) and quantity for identical beds.
- Adjust the mix ratio to match your preferred recipe.
- Press Calculate to see totals, mix breakdown, and bag counts.
- Use Export to download CSV or a printable PDF of results.
FAQs
Recommended Soil Depth by Crop
Use these inside depth targets to size soil volume realistically. Depths include the active rooting zone only.
| Crop category | Ideal soil depth | Notes |
|---|---|---|
| Leafy greens (lettuce, spinach) | 8–10 in (20–25 cm) | Shallow roots; prioritize compost quality. |
| Herbs (basil, cilantro) | 6–8 in (15–20 cm) | Lower depth ok; avoid waterlogging. |
| Root veg (carrot, beet) | 12–14 in (30–35 cm) | Uniform, stone‑free soil improves shape. |
| Fruit veg (tomato, pepper) | 12–18 in (30–45 cm) | Deeper beds buffer summer heat stress. |
| Potato, sweet potato | 12–16 in (30–40 cm) | Hilling adds functional depth over time. |
| Berry canes (raspberry) | 16–20 in (40–50 cm) | Consider drainage layer in heavy soils. |
Bulk vs Bag Sourcing — Conversions & Cost Guide
Quick reference using the default bag sizes (2 ft³ and 40 L). Round up in practice. Prices vary by region and supplier.
| Target volume | ft³ | yd³ | Liters | ≈ 2 ft³ bags | ≈ 40 L bags |
|---|---|---|---|---|---|
| Half yard | 13.5 | 0.5 | 382 | 7 | 10 |
| One yard | 27.0 | 1.0 | 765 | 14 | 20 |
| Two yards | 54.0 | 2.0 | 1,529 | 27 | 39 |
| Three yards | 81.0 | 3.0 | 2,294 | 41 | 58 |
Rule of thumb: delivery becomes economical around one yard or more.
Seasonal Mix & Settling Recommendations
Adjust compost share and top‑up allowance by season and organic content.
| Season / scenario | Suggested compost % | Suggested aeration % | Top‑up allowance | Notes |
|---|---|---|---|---|
| Early spring bed‑build | 30–40% | 10–15% | 15–20% | Fresh mixes settle more after first irrigations. |
| Mid‑season top‑up | 20–30% | 5–10% | 5–10% | Lower settling; focus on structure and moisture. |
| Autumn bed reset | 30–35% | 10–15% | 10–15% | Incorporate leaves/wood fines; cover over winter. |
| Heavy clay base | 35–45% | 10–20% | 10–15% | Prioritize drainage and organic matter to loosen. |
| Very sandy base | 25–35% | 5–10% | 10–15% | Add compost for water holding capacity. |