Ladder Angle Calculator
Work out the safe base distance and angle for a ladder against a wall using the 75-degree rule, free and instant in your browser.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the ladder length and the vertical height it reaches.
- Read the angle, base distance and safety check.
How it works
Angle = arcsin(height ÷ ladder length); base distance = √(length² − height²). The safe zone is about 75°.
Worked example
6 m ladder reaching 5.5 m. ≈ 66° — base 2.4 m out.
Common mistakes
- Setting the ladder too upright (tip-back risk) or too shallow (slide-out risk).
- Ignoring the 4:1 rule — 1 m out for every 4 m of height.
Frequently asked questions
What angle should a ladder be set at?
About 75° from horizontal — the 4-to-1 rule: one unit out from the wall for every four units of height — for safe footing.
How do I check ladder angle quickly?
Stand with toes at the feet and arms straight out; your palms should just reach the rung at shoulder height when the angle is about right.
What angle should a ladder be?
About 75° — the '4:1 rule': place the base 1 m out for every 4 m of working height. Always follow site safety rules.
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Cite this tool
Zerdly. (2026). Ladder Angle Calculator. Retrieved from https://www.zerdly.com/tools/ladder-angle-calculator/
Tip: Enter any known values to calculate the remaining results.
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