The 1 in 4 rule is the standard for setting a straight or extension ladder at the correct angle: for every 4 feet of vertical height, the ladder base should sit 1 foot away from the wall.

This ratio — also called the 4:1 rule — keeps the ladder stable by distributing your weight between the rungs and the wall contact point. Set the base too close and the ladder tips backward; too far out and it slides. The 1 in 4 rule applies to straight and extension ladders specifically. Step ladders are self-supporting and set up vertically, so the 4:1 angle rule doesn't govern them the same way — but the term is commonly associated with ladder safety broadly.

  • 1 in 4 rule ratio: 1 foot of base distance for every 4 feet of vertical height.
  • Equivalent angle: the 4:1 ratio produces approximately a 75-degree ladder angle.
  • Applies to: straight and extension ladders, not self-supporting step ladders.
  • Governing standard: ANSI/ASSC A14 series covers ladder safety requirements including placement angles.
  • Quick check method: stand at the base with toes touching the feet — outstretched arms should reach the rung at shoulder height.