Ladder Angle Calculator
Check your ladder angle against the HSE 1-in-4 rule (75° from horizontal) or calculate the required base distance for a given rise. Includes safety notes for access ladders.
Ladder Angle Calculator
HSE INDG455 / WAHR 2005Choose a mode: check an existing angle, or find the required base distance for your rise.
Safety Notes
Access ladders should extend at least 1 metre (about 5 rungs) above the landing. Secure the ladder and maintain 3 points of contact at all times.
Assumptions
Source: HSE Safe use of ladders and stepladders (INDG455); Work at Height Regulations (WAHR) 2005. The 1-in-4 rule gives a ladder angle of approximately 75° from horizontal — this is the HSE-specified ideal. Acceptable band approximately 73–78°. Values are guidance; always carry out a site-specific risk assessment.
Disclaimer
These results are estimates for guidance purposes only. Always carry out a site-specific risk assessment and follow the manufacturer's instructions for the ladder in use. This calculator does not constitute legal or professional advice.
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HSE 1-in-4 Rule Quick Reference
For every 4 m of rise, set the base 1 m out. This gives approximately 75° from horizontal.
| Rise (m) | Required base (m) | Angle |
|---|---|---|
| 2 | 0.50 | 76.0° |
| 3 | 0.75 | 76.0° |
| 4 | 1.00 | 76.0° |
| 5 | 1.25 | 76.0° |
| 6 | 1.50 | 76.0° |
Note: atan(4) ≈ 76.0°; the HSE-stated ideal is 75°, which is the rounded design target for the 1-in-4 ratio.
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