Work out fall arrest clearance instantly with clear inputs, formula shown and shareable results.
Required fall clearance is the sum of free fall, energy absorber deployment, harness stretch, the distance from the dorsal D-ring to the worker's feet, and a safety margin so the feet stop clear of the ground or obstruction. With a two metre lanyard and a shock absorber the total is typically well over six metres, which is why short lanyards or self-retracting devices are needed at lower heights.
Fall clearance
Clearance = lanyard length + absorber deployment + harness stretch + 1.5 m worker height + safety margin
Preliminary estimate only. Fall protection systems must be selected and installed under a competent person's plan using the manufacturer's clearance data.
Clearance = lanyard length + absorber deployment + harness stretch + 1.5 m worker height + safety margin. Required fall clearance is the sum of free fall, energy absorber deployment, harness stretch, the distance from the dorsal D-ring to the worker's feet, and a safety margin so the feet stop clear of the ground or obstruction.
Use a self-retracting lifeline, which limits free fall to under half a metre, or a work positioning or restraint system that prevents a fall from starting at all.
This calculator takes 4 inputs: Lanyard length, Energy absorber deployment, Harness stretch and D-ring slide, Safety margin below the feet. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.