Fall factor calculator
Type the distance of a fall and the length of rope or lanyard that holds it to see the fall factor, the ratio that climbing and rope access sources use to describe how serious a fall is.
Checked against the sources at the bottom of this page on October 8, 2026. Published tables are revised: the source has the last word.
Work it out
How the answer is worked out
Fall factor = the fall distance divided by the length of rope or lanyard that takes up the fall. It has no unit, since both lengths are changed to metres before the division.
The answer is also compared with 2, the top of the range that a 2020 study gives for a lanyard of fixed length.
What the sources say
In the International Journal of Environmental Research and Public Health, a 2020 paper on fall arrest lanyards takes the fall factor as the height of the fall, before the equipment is put into tension, divided by the length of the equipment that absorbs the fall energy. It says this is the criterion that ANSI A10.32:2004 uses, and that for a lanyard of constant length the fall factor lies between 0 and 2.
A 2009 symposium paper by Jim Kovach, Fall Factors: Do They Apply to Rope Rescue and Rope Access?, sets out older definitions. A 1982 mountaineering textbook gives the ratio of the length of the fall, leaving out rope stretch, to the total length of rope between climber and belayer, and says that the higher the fall factor, the greater the force. A 2001 working at height handbook describes it as the relationship between the length of the fall and the amount of rope available to spread the impact force. Rope access guidelines of a United States federal bureau, as the paper names them, define it as the maximum distance a worker can fall divided by the length of rope or lanyard connection between the falling worker and the anchor.
The same paper argues that fall factors do not apply to static ropes, and that for static rope the fall factor does not show how severe a fall is. It reports that a 2007 rope access practices document from SPRAT says dynamic rope should normally be used in place of static or low-stretch rope where a fall above factor 0.25 might occur. This page reports those views and takes no side.
The UIAA Safety Commission's answer on rope testing says the first test for one strand of a half rope, devised in the 1970s, was a single fall of fall factor 2 with an 80 kg mass. It says that test was turned into five falls with a 55 kg mass, as the equivalent of one fall with 80 kg.
The calculator divides two typed lengths. It does not know whether the anchor is above or below the user, how far the rope or lanyard stretches, or what force reaches the body.
Arithmetic only. The answer is only as good as the numbers entered. It is not a plan or a safe working load for any job.
Sources
- International Journal of Environmental Research and Public Health, via PubMed Central, Optimization on Personal Fall Arrest Systems: Experimental Dynamic Studies on Lanyard Prototypes, 2020, read October 8, 2026
- International Technical Rescue Symposium, Jim Kovach, paper Fall Factors: Do They Apply to Rope Rescue and Rope Access? November 2009, as hosted by the Vertical Section of the National Speleological Society, read October 8, 2026
- UIAA Safety Commission, answers to readers' questions on rope testing, read October 8, 2026
- NIST, Guide for the Use of the International System of Units (SP 811), Appendix B.8 factors for units listed alphabetically, read October 8, 2026