Ladder Angle Calculator
Find the right ladder angle for safe use. Enter your ladder length, wall height, or base distance to get the angle and a safety assessment.
Vertical height from ground to the top support point on the wall
Horizontal distance from the wall to the ladder base
Total length of the ladder
What is the 4:1 rule for ladder safety?
The 4:1 rule states that for every 4 feet of vertical height, the ladder base should be 1 foot from the wall. This sets the base distance at 25% of the working height, giving an approximately 75-degree angle from the ground. This rule is the industry standard and recommended by OSHA for extension ladder placement.
What is the safest angle for a ladder?
OSHA recommends positioning ladders at a 65-80 degree angle from the ground, with 75 degrees being optimal. Below 65 degrees, the ladder risks sliding out at the base. Above 80 degrees, the ladder becomes too vertical and risks tipping backward. The 4:1 placement rule naturally achieves approximately 75 degrees.
How do I measure the ladder angle without a protractor?
Use the 4:1 rule: stand at the base of the ladder with your toes touching the feet. Extend your arms straight out; your palms should just touch the ladder rungs at shoulder height. Alternatively, place the base at a distance equal to one-quarter of the working height. Most extension ladders have angle indicators on the side rails for reference.
What factors affect ladder stability beyond angle?
Beyond the correct angle, ensure the ladder is on firm level ground. Use ladder levelers on uneven surfaces. The top should contact both rails against a solid surface, never a gutter or window. Extend three feet above the roof line when accessing a roof. Always face the ladder, maintain three points of contact, and never overreach.