Ladder Angle Calculator — Safe Placement Angle
Enter the height the ladder must reach and the distance its base sits from the wall to instantly get the angle, the required ladder length, and whether the placement meets the recommended 70–78° safety range.
m
m
Angle is within the safe 70–78° range for ladder use
- 1
Height ÷ base ratio
4 ÷ 1 = 4 - 2
Angle in radians
arctan(4) = 1.3258 - 3
Ladder angle
1.3258 × 180 ÷ π = 76Multiply radians by 180/π to convert to degrees.
How does this calculator work?
Ladder angle = arctan(height ÷ base), ladder length = √(height² + base²). The classic 4-to-1 safety rule sets the base at height ÷ 4, giving roughly 75.5°. Enter height and base to get the exact angle and whether it falls in the recommended 70–78° safe range.
Formula
How this is calculated
A ladder leaning against a wall forms a right triangle with the ground and the wall. The height (opposite side) is the point on the wall where the ladder rests; the base (adjacent side) is the horizontal distance from the wall to the foot of the ladder; and the ladder itself is the hypotenuse. The angle at the base follows from trigonometry: θ = arctan(height ÷ base). The required minimum ladder length is √(height² + base²) by the Pythagorean theorem.
Safety guidance from occupational-health bodies (e.g. HSE in the UK, OSHA in the US) generally recommends a ladder angle of 70–78°, with 75–76° (roughly the classic "4-to-1 rule": base = height ÷ 4) as the ideal. At lower angles the feet can slip outward; at steeper angles the top can topple away from the wall. This calculator shows the recommended base distance for the ideal 75.5° angle so you can reposition the foot if needed.
All calculations assume a straight lean-to ladder on flat, level ground. Extension ladders, roof ladders, and step-ladders have their own safety rules. Always ensure the foot is on firm, non-slippery ground and the top is secured or held.
Frequently asked questions
For every 4 metres (or feet) of working height, set the base 1 metre (or foot) out from the wall. This gives approximately 75.5° — the center of the recommended safe range. For example, a ladder reaching 4 m high should have its foot 1 m from the wall.
Too shallow (low angle, wide base) puts excessive horizontal force on the feet and risks the ladder sliding outward. Too steep (near vertical) puts the top off-balance and risks the ladder toppling backward. The 70–78° sweet spot balances both risks.
Extend a tape measure horizontally from the base of the wall to where the ladder foot will sit on the ground. Do this on level ground. For uneven surfaces, the horizontal ground distance still drives the angle, but you may need a longer ladder to account for ground slope.
Also known as
TG we-Calculate Editorial Team. (2026). Ladder Angle Calculator — Safe Placement Angle [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/ladder-angle-calculator
TG we-Calculate Editorial Team. "Ladder Angle Calculator — Safe Placement Angle." TG we-Calculate. 2026. https://we-calculate.com/calculator/ladder-angle-calculator.
TG we-Calculate Editorial Team, "Ladder Angle Calculator — Safe Placement Angle," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/ladder-angle-calculator
@misc{wecalculate_ladder_angle_calculator, title = {Ladder Angle Calculator — Safe Placement Angle}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/ladder-angle-calculator}}, year = {2026}, note = {TG we-Calculate} }
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