Every nail grows at its own pace. As a rule of thumb, the longer the last leg of your finger, the faster the nail grows. The nail of your index finger grows faster than that of your little finger. But your thumb grows slowest - your thumb is missing a leg too. Your toes are shorter than your fingers and those nails grow about three times as slowly. Furthermore, your nails grow faster based on what you do most with. It has also been shown that your nails grow faster in summer than in winter, and faster when you are under 30.
Scientists don't know exactly why your nails don't all grow at the same speed, but it is probably related to the amount of blood - and therefore oxygen and nutrients - that the cells reach at the bottom of your nail root. The cells secrete the protein keratin, which deposits under the nails, causing them to grow.
Toenails take it easy
A fingernail grows approximately 0.1 millimeter per day and is therefore completely replaced in three to six months. The toenails are slower. It can take a year and a half before a nail that has fallen off has grown.