Ladder Angle Calculator

Work out ladder angle instantly with clear inputs, formula shown and shareable results.

About Ladder Angle Calculator

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.

Formulas

Ladder angle

Angle = arccos(base distance / ladder length)

One in four rule

Base distance = ladder length / 4 gives about 75 degrees

Worked example

With the default values below, Ladder Angle Calculator returns Ladder angle to the horizontal of 75.52. Change any input above and every figure here is recalculated in your browser.

Inputs used

Ladder length along the stileminimum 0.5 m: 6 m
Distance of the base from the wallminimum 0.05 m: 1.5 m

Results

Ladder angle to the horizontal: 75.52 °
Vertical height reached: 5.809 m
Base distance as a fraction of length: 0.2500
Assessment against the one in four rule: Correct angle — close to 75 degrees

Step by step

1Values used
2Ladder angle
3One in four rule
4Ladder angle to the horizontal= 75.52 °
5Vertical height reached= 5.809 m
6Base distance as a fraction of length= 0.2500
7Assessment against the one in four rule= Correct angle — close to 75 degrees

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
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.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

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.

Frequently Asked Questions

How is the Ladder Angle figure worked out?

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.

How far can the ladder extend above the landing?

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.

What values do I need to enter?

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.