Required Fall-Arrest Clearance (ANSI Z359)
The clearance a personal fall-arrest system needs below the anchor so the worker does not strike the level: RFC = free-fall distance + deceleration distance + worker height (D-ring to feet) + safety margin. A 6 ft free fall, 3.5 ft deceleration (the Z359 lanyard cap), 5 ft worker, and 3 ft margin needs 17.5 ft. Enter each explicitly - free-fall depends on the anchor position; an SRL cuts both the free-fall and deceleration. Per ANSI Z359.1 / OSHA 1926 Subpart M; the equipment instructions and a competent person govern.
Formula and source
required_clearance = free_fall_distance + deceleration_distance + worker_height (D-ring to feet) + safety_margin; margin = available_clearance - required_clearance; adequate when margin >= 0.
ANSI Z359.1 (Fall Protection Code) and OSHA 1926 Subpart M fall-clearance calculation, by name.
Audience
This tile is built for trades and the adjacent professions in the Fire-Ground Engineering group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.