Formula used
| Calculation | Formula |
|---|---|
| Rectangular perimeter | 2 × (length + width) |
| U-shaped perimeter | 2 × (outer width + outer length) + 2 × opening depth |
| Horizontal courses | Ceiling(wall height ÷ actual board width) |
| Vertical boards | Ceiling(perimeter ÷ actual board width) |
| Wall lumber length | Perimeter × courses × bed count |
| Mid-span posts | Ceiling(segment length ÷ post spacing) − 1 |
| Soil volume | Growing area × soil depth × bed count |
| Board feet | Thickness(in) × width(in) × length(ft) ÷ 12 |
| Total cost | Subtotal + tax or VAT |
How to use
- Select the raised bed layout and measurement unit.
- Enter outer dimensions, height, and bed quantity.
- Choose actual board dimensions and available stock length.
- Select posts, caps, liners, braces, and accessories.
- Add local prices, waste allowance, tax, and delivery.
- Calculate, then review the shopping and cutting lists.
Example data
| Field | Example | Purpose |
|---|---|---|
| Layout | Rectangular | Standard four-sided bed |
| Length × width | 8 ft × 4 ft | Common household size |
| Wall height | 1.5 ft | Three to four courses |
| Actual board | 1.5 in × 5.5 in | Typical nominal 2×6 |
| Stock length | 8 ft | Common retail board |
| Post spacing | 4 ft | Controls long-wall bowing |
| Waste | 10% | Allows defects and mistakes |
Frequently asked questions
Does nominal board size equal actual size?
No. Finished lumber is usually smaller than its nominal label.
How much waste should I include?
Ten percent suits simple beds. Complex cuts may need more.
When are support posts needed?
Long walls need posts to resist bowing from wet soil.
Can the calculator handle U-shaped beds?
Yes. Enter outer dimensions, opening width, and opening depth.
What does cutting optimisation do?
It packs required cuts into stock boards with reduced waste.
Is saw kerf included?
Yes. Kerf is added between cuts on each board.
How are vertical boards calculated?
Perimeter is divided by actual board width, then rounded upward.
Does soil volume include settling?
No. Add extra soil separately for expected settlement and compaction.
Can composite boards use this calculator?
Yes. Select composite, then enter its actual dimensions and price.
Are structural results guaranteed?
No. Local conditions and engineering requirements can change support needs.
Can I save the estimate?
Yes. Copy, CSV, PDF, and print controls are provided.