This roof rafter length reference table shows the rafter length for a range of horizontal run values, assuming a vertical rise of 2 m and an overhang of 0.3 m. Every figure is computed with the same engine that powers our Roof Rafter Length Calculator, so the numbers are exact.
| Horizontal run | Rafter length | Sloped length (no overhang) |
|---|---|---|
| 1 m | 2.536 | 2.236 |
| 2 m | 3.128 | 2.828 |
| 3 m | 3.906 | 3.606 |
| 4 m | 4.772 | 4.472 |
| 6 m | 6.625 | 6.325 |
| 8 m | 8.546 | 8.246 |
| 12 m | 12.466 | 12.166 |
| 20 m | 20.400 | 20.100 |
| 28 m | 28.371 | 28.071 |
| 40 m | 40.350 | 40.050 |
How to use this table
Find the row closest to your horizontal run and read across to the rafter length. For a value between two rows, the real figure sits between them — or enter your exact numbers in the Roof Rafter Length Calculator for a precise answer.
Need a value that is not in the table? — the Roof Rafter Length Calculator does it instantly, for free, with the formula and a worked example built in.
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