Fall factors

Fall Factors measure the relative severity of a fall in terms of the shock loads placed upon the equipment and user.

The formula

Fall Factor (FF) = Length of fall ÷ Length of rope holding the fall

Drag the sliders to see how anchor position and lanyard length combine into fall factor and peak rope tension.

Limits in practice

It is important to ensure that the Fall Factor is kept to a minimum.

• Dynamic rope is capable of withstanding a FF2 fall when new — but good practice is not to exceed FF1.
• Low Stretch rope — good practice is not to exceed FF 0.3.

Scenario	Fall Factor
Anchor above the user, fall ≤ rope length used	FF 0
Anchor at user's feet, fall = rope length used	FF 1
Anchor below user, fall = 2× rope length used	FF 2

Lead climbing

During lead climbing situations, any potential fall should be mitigated by the use of appropriately spaced 'Running Belays' to reduce the fall height — and thus the Fall Factor — placed on the system.

The higher a climber ascends with sufficient running belay protection, the lower the resulting Fall Factor. The overriding consideration is reducing any potential fall height.

Beyond FF2 — via ferrata

In some situations it is possible to generate Fall Factors in excess of FF2.

Example: if you were clipped to the handrails on a bridge suspension cable and you fell, the fall height would be calculated from the height at which you fell to the height at which your fall was arrested. On the Humber Suspension Bridge this height could in some cases be as much as 4 m. With a 1 m cow's tail the fall factor would be FF4.

This does not allow for the friction between the handrail and the cow's tail carabiner slowing down the fall — but it highlights the potential for very high Fall Factors.

Some equipment manufacturers produce energy absorbers specifically for high Fall Factor situations.