Fingernails grow faster on the hand you use most, in many cases.

The longer version

Nail growth depends on how fast new cells are produced in the living tissue at the base of the nail, just under the cuticle. As those cells divide, older ones are pushed forward, flatten and harden with keratin, and become the visible plate. Blood supply and oxygen delivery matter here, since dividing cells need a steady stream of raw material.

Anything that increases blood flow or mild repeated stimulation to a hand can nudge that cell division along, which is why the hand used most often frequently shows slightly faster growth. The effect is small and varies a lot between people, and factors like age, season and general circulation also shift the rate. Growth also tends to slow with advancing age, so the plate takes longer to replace.

Where this entry sits

These facts look at how the human body works in ordinary moments, from breathing and blinking to balance and sleep. They focus on anatomy, senses, and small reactions that happen constantly without any conscious effort. The full list sits on the Human Body page, where every entry is listed in order.