Ladder Safe Angle
The lean angle is the inverse cosine of the base distance over the ladder length. The safe band is 70–80°, and setting the foot out a quarter of the length lands near 75.5°.
Your numbers
Angle (°)
75.52°
Height reached
3.873m
Distance from wall
1m
What it means
75.52° is inside the recommended 70–80°. Standing the foot a quarter of the length out gives about 75.5°.
Formula
Angle (°) = acos(Distance from wall ÷ Ladder length)
The height reached is shown too. Treat the usable height as three rungs less than that.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Ladder length (m)The full length of the ladder, measured extended. | 4 | 0.1 and up |
| Distance from wall (m)The distance from the foot of the ladder to the wall. | 1 | 0 and up |
Step by step
Quick reference table
Results when only Ladder length (m) changes and everything else stays put.
| Ladder length (m) | Angle (°) (°) | Height reached (m) | Distance from wall (m) |
|---|---|---|---|
| 2 | 60 | 1.732 | 0.5 |
| 3 | 70.53 | 2.828 | 0.75 |
| 4 | 75.52 | 3.873 | 1 |
| 6 | 80.41 | 5.916 | 1.5 |
| 8 | 82.82 | 7.937 | 2 |
What each result means
| Result | At default values |
|---|---|
| Angle (°) (°)An angle in degrees; a full turn is 360°. | 75.52 |
| Height reached (m)How high up the wall the top of the ladder reaches. | 3.873 |
| Distance from wall (m)The distance from the foot of the ladder to the wall. | 1 |
Common mistakes
The height reached is shown too. Treat the usable height as three rungs less than that.
Glossary
- Ladder length
- The full length of the ladder, measured extended.
- Distance from wall
- The distance from the foot of the ladder to the wall.
- Angle (°)
- An angle in degrees; a full turn is 360°.
- Height reached
- How high up the wall the top of the ladder reaches.
Frequently asked questions
Q. How is Ladder Safe Angle calculated?
Angle (°) = acos(Distance from wall ÷ Ladder length) — The lean angle is the inverse cosine of the base distance over the ladder length. The safe band is 70–80°, and setting the foot out a quarter of the length lands near 75.5°.
Q. Can you walk through an example?
With Ladder length 4m, Distance from wall 1m, the answer is Angle (°) 75.52°.
Q. What do I need to enter?
Enter Ladder length, Distance from wall. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Ladder length (m) moves the answer to Ladder length (m) 2 → Angle (°) (°) 60 and Ladder length (m) 8 → Angle (°) (°) 82.82. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
The height reached is shown too. Treat the usable height as three rungs less than that.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.