Estimate base setback and ladder length from the height of the top support and the lean angle.
| Base | – |
| Ladder | – |
Use this calculator to set a ladder against a wall. Enter the height of the top support and the lean angle from the ground. A common safe lean is about 75° (the 4-to-1 rule).
Base = height ÷ tan(angle). Ladder length = height ÷ sin(angle). Height can be entered in metres (m) or feet (ft). Base and ladder length follow the same unit. Angle is in degrees from the horizontal.
This is a right-triangle layout. It does not check ladder rating, a 1 m extension above the eaves, or a tie-off.
Height: Height of the top support, in m or ft.
Angle: Lean from the ground in degrees. 75° is a typical 4-to-1 lean.
Base: Distance from the wall to the feet.
Ladder: Required ladder length.
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