What’s a kilonewton? Physics 101 for climbers

When you check carabiners for their rated strength, you’ll find it expressed in metric units of force called kilonewtons (kN).  The kN rating measures the amount of force it would take to break a piece of equipment, as opposed to a static weight.  That’s why Kn is used rather than a static weight.  A biner rated at 22kN (4945 lbf) could be expected to break if the load of a fall equaled this value.

A newton is the force required to accelerate a one-kilogram mass one meter per second per second.  The simplistic conversion is one kN = about 225lbs.  Thus, a typical biner rated to 20 kN can, under ideal circumstances, take a load of about 4,500 pounds.  (“Ideal circumstances” are rarely found while falling in the real world, but rest assured - a 20 kN biner should be more than strong enough for your climbing.) 

Attn gearheads:  Force (N) = Mass (kg) x Acceleration (m/sec2) 1000 N = 1 kN 1kN = 224.8 lb force.