Formula and input notes
Base distance = vertical height ÷ tan(angle); ladder length = vertical height ÷ sin(angle)
| Input | Practical note |
|---|---|
| Ladder angle | The angle is measured from horizontal and drives both base setback and working length. Confirm the required setup with the manufacturer and applicable rules. |
Worked ladder angle example
Ladder Angle Calculator example: At 75°, a 13.38-ft vertical height gives 3.59 ft of base distance and a geometric minimum ladder length of 13.85 ft. Required top extension is not included.
Use the triangle as a setup check
Use the geometry only as a reasonableness check, then follow the ladder label, manufacturer instructions, and site safety procedure.
Setup conditions the triangle cannot verify
Top extension, rung position, nonlevel ground, ladder flex, user reach, manufacturer setup marks, and obstructions affect safe placement.
Questions specific to this calculation
What does the entered ladder angle control?
The angle sets the right-triangle relationship among vertical reach, horizontal base distance, and working length. A steeper angle shortens the base distance; a shallower angle increases both base distance and required length.
Does the calculator approve a ladder setup?
No. Confirm the ladder type, rated length and load, support, extension above the landing, securing method, surface conditions, and the manufacturer's instructions. Workplace rules may impose additional requirements.
For U.S. construction workplaces, review the applicable OSHA ladder requirements and the ladder manufacturer's instructions before use.