Ladder Angle Calculator

What Is a Ladder Angle Calculator?

A ladder angle calculator finds the angle between a ladder and the ground from reach height and bottom distance. It also computes working ladder length and checks the 4-to-1 safety rule used on job sites and for home maintenance.

The 4-to-1 Ladder Rule

For every 4 feet of vertical reach, move the ladder base 1 foot away from the wall. A 12-foot reach needs a 3-foot bottom offset. This gives about a 75-degree angle, which OSHA and ladder manufacturers recommend for stable setup.

Ladder Angle Formulas

Angle from reach $R$ and bottom distance $B$:

$$\alpha = \arctan\left(\frac{R}{B}\right)$$

Working ladder length:

$$L = \sqrt{R^2 + B^2}$$

Pair this with the Roofing Calculator when working at roof height, or the Area Calculator for surface planning.