Ladder Placement Angle
Base distance for the 4:1 rule and pass/fail at 75.5 deg.
Example
You enter
- Ladder length (ft) 16
- Working height (ft) 12
You get
- Set angle 48.6 deg
- Base distance 4.00 ft
Checked against published worked examples from: OSHA.
Details, formula, and sources
Formula or table4:1 rule: base distance = working_length / 4. Angle θ = asin(working height / ladder length); pass within 3° of the 75.5° (4:1) target, 72.5-78.5°, per the ANSI portable-ladder standards A14.1 / A14.2 / A14.5.
Source and editionANSI/ASC A14.1 (wood), A14.2 (metal) and A14.5 (reinforced plastic) portable ladders, which set the 75.5° (4:1) setup angle, by name; OSHA 29 CFR 1926.1053 by section. A14.7 covers mobile ladder stands, not leaning ladders.
Free access29 CFR 1926.1053 free at ecfr.gov; ANSI standards licensed.
What governsEstimate. AHJ and licensed professional govern.
API field namesladder_length_ft, working_height_ft, set_angle_deg, base_distance_ft
- Pass-fail target 75.5° (4:1)ANSI A14.1 / A14.2 / A14.5