CrewMeasure

Ladder Angle Calculator

Ladder angle and length from rise and run, checked against the OSHA 1:4 recommendation.

Set the ladder base — ft out for a —° climbing angle.

Ladder angle inputs

Rise is the height climbed; run is the base distance from the wall.

Set the ladder base — ft out for a —° climbing angle.

Set base at

Ladder angle results

Warnings

  • ERROR Enter a rise greater than zero.
  • ERROR Enter a run (base distance from the wall) greater than zero.

Detail values

Within 2° of the OSHA ~75.5° (1:4) angle
—
Angle
—°

Assumptions

  • Recommended angle: ~75.5 deg -- arccos(1/4), from the 1:4 base-to-working-length ratio OSHA 1926.1053(b)(5)(i) requires. That section's own word is "approximately" and it publishes no tolerance in degrees, so the +/-2 deg band this screen passes or fails on is CrewMeasure's, not the regulation's
  • Working length: The length this screen prints is the WORKING length OSHA 1926.1053(b)(5)(i) defines -- "the distance along the ladder between the foot and the top support" -- and it is not the ladder to buy. Where a ladder is used to gain access to an upper landing, 1926.1053(b)(1) requires the side rails to extend at least 3 ft above that landing; or, where the ladder's length makes that impossible, that the ladder be secured at its top to a rigid support that will not deflect and a grasping device be provided. This screen does not ask whether the climb ends at a landing, so nothing is added here for it. An extension ladder also reaches less than its nominal length, by the overlap between its sections.

Included: ladder length, climbing angle check.

Not included: labor, verification against manufacturer or local-code specifics beyond the reference table used, material waste from cutting.

Formula details
  • Ladder angle: atan(rise / run)
  • Working length (foot to top support): sqrt(rise^2 + run^2)
Material List

About this calculator

Enter rise (height climbed) and run (base distance from the wall) to get the ladder's angle and length.

FAQ

What is the OSHA 1:4 rule?

OSHA recommends setting extension ladder base distance at roughly 1/4 of the working length, producing an angle of about 75.5 degrees -- a practical safety reference, not a strict numeric code requirement for every situation.