Free calculator
Set the ladder at the right angle.
Enter the height where the ladder rests, or the length of the ladder. You'll get how far out to set the foot, and the angle it makes.
Also called4 to 1 ladder rule calculator, Ladder setup calculator, Ladder distance from wall
Result
Foot out from the wall
--ft
Height reached
--ft
The 4 to 1 rule: for every 4 feet of height, the foot of the ladder sits 1 foot out. That makes an angle of about 75.5 degrees. A ladder used to reach a roof or landing should extend at least 3 feet above it. Check the current OSHA ladder rules and the maker’s label.
This does arithmetic on what you type. Nothing leaves your browser. Check the result against your own rules and procedures.
The 4 to 1 rule
- For a leaning ladder, set the foot one foot out for every four feet of height where the ladder rests. That makes an angle of about 75.5 degrees. In OSHA's ladder rules, the horizontal distance from the foot to the top support is about one quarter of the working length.
Before you climb
- A ladder used to reach a roof or landing should extend at least 3 feet above it.
- Set it on firm, level ground, and secure the top or have someone hold the foot, per your procedure.
- Check the duty rating and the maker's label. Check the current OSHA ladder rules.
Run this in the field.
Check a ladder before use on a phone, with a photo of any damage, no signal needed.
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Common questions
- What is the 4 to 1 ladder rule?
- It's a setup rule for leaning ladders. The base sits one foot away from the wall for every four feet of height up to where the ladder rests.
- Does the rule apply to step ladders?
- No. Step ladders are self-supporting and are opened fully with the spreaders locked. The 4 to 1 rule is for straight and extension ladders that lean on a support.
- How far above the roof should a ladder reach?
- At least 3 feet above the upper landing, so a person has something to hold when stepping on and off. Check the current OSHA ladder rules.
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