Sleeper calculator: raised beds and cut list
The calculator needs JavaScript. The worked example, formula and figures below show exactly how it works, so you can do the sum yourself. A guide, not advice. Check your supplier's or maker's figures before ordering.
Short answer
Worked example
| You enter | Value |
|---|---|
| Length of the long sides | 2.4 m |
| Length of the ends | 1.2 m |
| Courses | 2 |
| Sleeper length | 2.4 m |
| Height of each course | 200 mm |
| Sleeper thickness | 100 mm |
| Saw cut width | 0 mm |
| Topsoil density | 1.4 t/m³ |
Order: 6 sleepers
| Result | Value |
|---|---|
| Sleepers | 6 |
| Left over | 0 m |
| Bed height | 400 mm |
| Soil to fill it | 1.056 m³ |
| Soil to fill it (weight) | 1.48 t |
| Length | Cut into | Offcut |
|---|---|---|
| 1 (2.4 m) | Course 1 side A: 2.4 m | 0 m |
| 2 (2.4 m) | Course 1 side B: 2.4 m | 0 m |
| 3 (2.4 m) | Course 2 side A: 2.4 m | 0 m |
| 4 (2.4 m) | Course 2 side B: 2.4 m | 0 m |
| 5 (2.4 m) | Course 1 end A: 1.2 m; Course 1 end B: 1.2 m | 0 m |
| 6 (2.4 m) | Course 2 end A: 1.2 m; Course 2 end B: 1.2 m | 0 m |
Show the working
- Each course: 2 × 2.4 m sides + 2 × 1.2 m ends; 2 courses = 8 pieces
- Packed into 2.4 m sleepers: 6 sleepers (14.4 m bought, 14.4 m used, 0 joins)
- Height: 2 × 200 mm = 400 mm
- Inside: (2.4 − 2 × 0.1) × 1.2 × 0.4 m = 1.056 m³
- Soil: 1.056 m³ × 1.4 t/m³ = 1.48 t
How it works
- Each course is two long sides and two ends; the ends fit between the long sides
- Pieces are packed into sleeper lengths longest first (first-fit decreasing); a side longer than a sleeper is made from more than one
- Bed height = courses × course height; inside the bed = (long side − 2 × thickness) × end length × height
- Soil (t) = inside volume × topsoil density; screws = 4 corners × courses × screws per corner
For a bed that retains soil higher than 0.6 m, on a slope, or next to a path or boundary, get a structural design: that is out of scope here.
Our default (adjustable)
These are typical planning figures and our own allowances, not facts about your product. Change any of them in the calculator to match your bag, pack or tin.
| Figure | Our default (adjustable) | Kind | Source |
|---|---|---|---|
| Sleeper length | 2.4 m | Common UK size Not yet checked against the source | From your product brief v2 L8 (2.4 m × 200 × 100 sleeper). Check the product. |
| Height of each course | 200 mm | Common UK size Not yet checked against the source | From your product brief v2 L8 (2.4 m × 200 × 100 sleeper), laid on its 100 mm edge so each course is 200 mm high. |
| Sleeper thickness | 100 mm | Common UK size Not yet checked against the source | From your product brief v2 L8 (2.4 m × 200 × 100 sleeper). |
| Topsoil density | 1.4 t/m3 Sources range 1.4–1.5 t/m3 | Typical value Not yet checked against the source | rospower.co.uk tonnage calculator (exact page to confirm) (checked 19 October 2026) |
| Tallest bed this page covers | 0.6 m | Our assumption Not yet checked against the source | Our choice: change it to suit your job brief v2 L8: retaining over 0.6 m is out of scope (structural). A Plankley scope boundary, not a regulation. |