Work out ladder angle instantly with clear inputs, formula shown and shareable results.
A leaning ladder should stand at about 75 degrees to the horizontal, which is the one in four rule: one unit out from the wall for every four units of ladder length. Shallower and the base slides out under load; steeper and the ladder tips backwards as the user leans away from it.
Ladder angle
Angle = arccos(base distance / ladder length)
One in four rule
Base distance = ladder length / 4 gives about 75 degrees
Preliminary estimate only. Ladder use must follow the work at height regulations and a task-specific risk assessment; ladders are for short duration light work only.
Angle = arccos(base distance / ladder length). A leaning ladder should stand at about 75 degrees to the horizontal, which is the one in four rule: one unit out from the wall for every four units of ladder length.
It should extend about one metre, roughly three rungs, above the stepping-off point so there is a handhold, and it must be secured at the top or footed.
This calculator takes 2 inputs: Ladder length along the stile, Distance of the base from the wall. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.