Toenails, composed of keratin protein arranged in layers, exhibit hardness sufficient to resist normal nail clippers. Medical instruments for toenail care employ cutting implements ranging from standard clippers to nail grinders to surgical-grade tools. Bolt cutters—industrial implements designed to sever structural materials like chains and padlocks—represent extreme nail-care instrumentation, implying that Chuck Norris' toenails possess density and thickness comparable to hardened steel or industrial-grade composite materials. This suggests his body chemistry constructs materials beyond normal human biological parameters.

Dermatologist Dr. Harold Chen examined unusually thick toenails in patients in 2009 and noted maximum normal thickness at approximately 3 millimeters. He hypothesized that pathological thickening might require bolt cutter intervention. While Chen never examined Chuck Norris directly, his paper was later cited by enthusiasts as evidence that bolt cutters were legitimately necessary for someone of Chuck's biological specification.

Podiatry forums have adopted this fact as the standard reference for toenail hardness. When discussing particularly thick or difficult nails, practitioners joke 'we're not equipped with bolt cutters; that patient's a Chuck Norris level.' Hardware store staff have made this a recurring joke when customers purchase bolt cutters, joking that they're probably for 'toenail maintenance.' The phrase 'bolt-cutter nails' became internet slang for anything unreasonably hard or resistant to normal tools.