A straight or extension ladder is safest at the 4:1 angle — one foot of base distance for every four feet of working height (about 75°). Enter your working height to get the correct base setback and ladder length, and the 3-foot extension above the landing (OSHA 1926.1053 / ANSI A14).
The 4:1 rule
- Base setback = working height ÷ 4.
- Extend the rails 3 ft above the landing if you step off at the top.
- Tie off the top, keep three points of contact, and don’t stand on the top two rungs.
Working at height
FAQ
How do I check the angle without measuring?
Stand with your toes at the ladder feet and extend your arms straight out — your palms should just reach a rung at shoulder height. That is roughly the 4:1 (75°) angle.
Why extend 3 feet above the landing?
It gives you a secure handhold to grip while stepping on and off, the leading cause of ladder falls at the top.
General guidance per OSHA 29 CFR 1926.1053 and ANSI A14. Applies to non-self-supporting (straight/extension) ladders. Always inspect the ladder, ensure firm footing, and follow the duty-rating and manufacturer’s instructions.
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