How fast do fingernails grow?
Fingernails grow about 3.5 millimeters a month on average. Toenails grow more slowly, at about 1.6 millimeters a month, so a lost toenail can take a year or more to regrow.
Nails are made of keratin, the same tough protein found in hair. They grow from an area under the skin at the base of the nail called the matrix. New cells push older ones forward, and the visible nail plate is made of hardened dead cells. The pale half-moon at the base, called the lunula, is part of the matrix.
A fingernail takes about four to six months to grow out completely. Toenails take 12 to 18 months. Nails grow faster in young people, in summer and on the dominant hand. The nail on the middle finger often grows fastest, and the thumbnail grows slowest.
Clues to health
Changes in nails can sometimes point to health problems. Deep lines across the nails, called Beau's lines, can appear after a serious illness. Spoon-shaped nails may suggest iron deficiency. Doctors may look at nails as part of an examination, though most nail changes are harmless.
Did You Know?
The record for the longest fingernails on a pair of hands belonged to Lee Redmond of the US, whose nails reached a total length of about 8.65 meters in 2008.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.