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Extension Ladder Setup Angle & Placement Safety Checker

Check a non-self-supporting portable ladder's setup angle and landing extension against OSHA's 4:1 placement rule.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax
26.25 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Base-distance-to-working-length ratio

4 :1 (target 4:1)

High confidence

This restates OSHA 29 CFR 1926.1053's fixed setup-angle (4:1, ~75.5°) and landing-extension (3 ft minimum) rules only. It does not check ladder duty rating/load capacity, the condition of the ladder or the surface it rests on, tie-off/securing requirements, or overall fall protection needs for the specific task — those must be verified separately by the user each time the ladder is set up.

Resulting ladder angle from horizontal
75.52 °(target ~75.5°)
Landing extension
3.28 ft (OSHA min 3 ft)

For the dimensions entered, expect a base-distance-to-working-length ratio of 4 :1 (target 4:1). Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Per OSHA 29 CFR 1926.1053(b)(5)(i) (verified against the regulatory text): 'Non-self-supporting ladders shall be used at an angle such that the horizontal distance from the top support to the foot of the ladder is approximately one-quarter of the working length of the ladder' — the standard 4:1 ratio, corresponding to a ladder angle of approximately 75.5° from horizontal. Per 1926.1053(b)(1) (verified): when used for access to an upper landing surface, 'the ladder side rails shall extend at least 3 feet (.9 m) above the upper landing surface.'

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Frequently asked questions

What is OSHA's 4:1 rule for ladder setup angle?
Per 29 CFR 1926.1053(b)(5)(i), a non-self-supporting ladder must be set up so the horizontal distance from its base to the wall/support is approximately one-quarter of the ladder's working length — a 4:1 ratio, which works out to a ladder angle of about 75.5° from horizontal.
How far must the ladder extend above the landing it's used to access?
Per 29 CFR 1926.1053(b)(1), when the ladder is used to access an upper landing surface, its side rails must extend at least 3 feet (0.9 m) above that landing surface.
Does this check the ladder's condition, load rating, or tie-off?
No. This tool restates only OSHA's fixed setup-angle and landing-extension rules. It does not check ladder duty rating/load capacity, the condition of the ladder or the surface it rests on, tie-off/securing requirements, or overall fall protection needs — those must be verified separately by the user every time the ladder is set up.