Factors of the Rope First we calculate k of our rope. My personal rope has a static elongation factor of 6%. This number is determined by the UIAA (a climbing safety organization with a foreign name). initial length of rope=2.5m + 300mm=2.8m total. $F=80*9.806$ according to the manufacturer's website, static elongation=6% m=80kg F=80*9.806 $△l=2.$$8*106\text{\%}-2.8$ $k=F/△l=784.48/$$0.168/\mathrm{1000=4.7kN/m}$ $\mathrm{}But\; the\; spring\; constant\; is\; not\; as\; constant\; as\; the\; name\; may\; suggest.\; Because\; the\; length\; of\; rope\; being\; used\; in\; the\; system$changes depending on use, the change in length also changes. Lets redo the calculations knowing this and for any weight. $△l=x*6$$△l=x*6$, where x is the total length of rope in the system. k = F/△l=$9.806*m/x*0.$$06*1000=0.1634*m/\mathrm{x, }$$$ $where\; m\; is\; the\; mass\; of\; the\; climber\; and\; x\; is\; the\; tota$$l\; length\; of\; rope\; in\; the\; system\; (from\; belayer\; to\; the\; climber)$ https://www.theuiaa.org/safety-standards/