# Ladder Angle Calculator

URL: https://speedycalculator.com/calculators/construction/ladder-angle/
Last updated: 2026-10-25

> The ladder angle calculator finds the height a ladder reaches and its angle from the ladder length and base distance, checks it against the safe 75.5° (4-to-1) angle and tells you where to place the foot.

## Inputs

- Ladder length (working) (ft, m, in, yd, cm)
- Base distance from wall (ft, m, in, yd, cm)

## Results

- Height reached
- Ladder angle
- Ideal base distance (75.5°)
- Height at ideal angle

## Formula

```
Height = √(L² − base²)
Angle = acos(base ÷ L)
Ideal base = L ÷ 4 (75.5°)
```

## Explanation

OSHA and ladder manufacturers recommend the 4-to-1 rule: for every 4 ft of height to the support point, move the base out 1 ft. That gives an angle of about 75.5°. Too steep and the ladder can tip backwards; too shallow and the base can slide out. When accessing a roof, the ladder should extend 3 ft above the edge.

### How to use the Ladder Angle Calculator

- **Ladder length (working)**
- **Base distance from wall**
- Every result field is editable: type into **Ladder angle** and **Base distance from wall** plus every other field update to match.

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the ladder length and the distance of its foot from the wall. The calculator returns the height reached, the angle and the ideal base distance. Type a target angle or height to find the base distance.

### Tips for an accurate estimate

- Take measurements at floor level and at the ceiling – walls and rooms are often slightly out of square.
- Use the manufacturer's coverage, spacing and installation data when it differs from the typical values here.
- Keep a little extra of every finish material for touch-ups and repairs later.
- Check local building codes and permits before structural, electrical, plumbing or gas work.

### Common mistakes to avoid

- Sizing heating or cooling equipment by area alone when insulation, windows and climate make a big difference.
- Buying too little paint, stain or flooring and ending up with mismatched batches.
- Overlooking the extra material for steps, railings, gables and trim.

### Inputs explained

FieldWhat to enterLadder length (working)Units: ft, m, in, yd, cmBase distance from wallUnits: ft, m, in, yd, cm

### What each result means

- **Height reached** = sqrt(max([Ladder length (working)]^2 - [Base distance from wall]^2, 0))
- **Ladder angle** = deg(acos(min([Base distance from wall]÷[Ladder length (working)], 1)))
- **Ideal base distance (75.5°)** = [Ladder length (working)]÷4
- **Height at ideal angle** = [Ladder length (working)]×sqrt(15)÷4

### Example values

How the main result changes when **Base distance from wall** changes and everything else stays at the example values above:

Base distance from wall (ft)Ladder angle (°)2.582.83.7579.2575.56.2571.87.5681060

## Worked example

Inputs — Ladder length (working): 20 ft; Base distance from wall: 5 ft.

Results — Height reached = 19.36 ft; **Ladder angle = 75.5 °**; Ideal base distance (75.5°) = 5 ft; Height at ideal angle = 19.36 ft.

## FAQ

**What is the safe angle for a ladder?**
About 75.5°, which is the 4-to-1 rule: 1 ft out for every 4 ft up.

**How tall a ladder do I need for a 16 ft roof edge?**
About 20 ft for the angle plus 3 ft above the edge – a 24 ft extension ladder.

**Does the overlap of an extension ladder reduce its length?**
Yes – a 24 ft extension ladder with 3 ft overlap has about 21 ft of working length.

**What formula does the Ladder Angle Calculator use?**
Height = √(L² − base²).


## Sources

- [OSHA 1926.1053 – Ladders](https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.1053)