Calculating Your Fall Distance

When it comes to fall protection at a construction site, having the proper distance measured out can not only limit the impact of a fall but also limit the possibility of injury during that fall. Let’s review the proper calculations you’ll need to take when using both shock absorbing lanyards as well as retractable lifelines. We’ll use average numbers as an example.

Fall Distance Calculation with Shock Absorbing Lanyard & D-Ring Connector
One of the most commonly used shock absorbing lanyards is the six foot variety. Let’s give that a whirl in this example. The lanyard is 6 ft. long, and the max elongation of the absorber during deceleration would be 3.5 ft. An average construction worker is about 6 ft. tall. Let’s add all of those together.

To properly calculate our fall distance, we should add human or product error into the equation. Let’s assume the worker is taller than 6 ft., the harness wasn’t properly fitted, or you miscalculated your distance somewhere else in the equation. Add 3 ft. as a precaution. That leaves us with our suggested safe fall clearance distance of 18.5 ft.

    6 + 3.5 + 6 + 3 = 18.5 ft.

It’s worth noting that you’ll need to add the length of any anchorage connectors or D-rings you happen to use to this equation to get a better calculation of your clearance distance.

Fall Distance Calculation with Retractable Lifeline
What would a suggested fall clearance distance be for a retractable lifeline? A few different factors come into play with this one. Again, let’s consider the worker is of average height for this example.

You’ll need to combine the maximum free fall distance of your lifeline with the max deceleration distance. Most models will have those distances measured out to be 2 ft. and 3.5 ft., respectively. We’ll stick with that for this scenario.

Like last time, let’s toss in a buffer zone to account for human error or a too-tall worker. Tack on 3 ft. to your calculation. That leaves us with a suggested safe fall clearance distance of 14.5 ft.

    2 + 3.5 + 6 + 3 = 14.5 ft.

Just like in the first example, you’ll need to take the length of any added anchorage connectors or D-rings to get a proper calculation for your fall clearance distance.

Don’t cut corners when it comes to protecting yourself and your workers! Plan accordingly, make sure there is clearance space for a potential fall, and calculate fall distances appropriately. Need a short hand version of this? Check out the graphic on our site.