Nails grow about 0.1 mm (or about .004 inch) per day.
Fingernails tend to grow a little faster than toenails.
Toenails are approximately twice as thick as fingernails.
In general, nails tend to grow faster in summer than they do in the winter.
Men’s nails usually grow faster than women’s nails.
Nails on your dominant hand tend to grow faster.
From: Why Do Men Have Nipples? By: Mark Letner and Billy Goldberg, M.D.