Fingernails grow roughly 3.47 millimeters per month, which adds up to about 42 millimeters (1.7 inches) per year. Toenails are much slower, averaging 1.62 millimeters per month, or just under 20 millimeters (0.8 inches) annually. Those numbers represent averages for healthy adults, and your actual rate depends on your age, which finger or toe you’re looking at, and even which hand you use more.
Fingernail vs. Toenail Growth
Fingernails grow more than twice as fast as toenails. At the average rate, a fingernail takes about 4 to 6 months to completely replace itself from base to tip. A toenail can take up to 18 months for a full replacement. This is why a lost or damaged toenail feels like it takes forever to come back, while a broken fingernail fills in relatively quickly.
The difference comes down to blood flow. Your fingers have a richer blood supply and experience far more daily contact and stimulation than your toes, which spend most of the day tucked inside shoes. That constant use signals the nail-producing cells to keep dividing.
How Nails Actually Grow
Nails are produced by a cluster of cells called the nail matrix, which sits just beneath the skin at the base of each nail. These cells divide rapidly and begin filling up with a tough protein called keratin. As newer cells push forward, the older ones lose their nuclei, harden, and become the visible nail plate. The process is continuous, so the nail you can see is made entirely of compacted dead cells being shoved outward by the living ones behind them.
The white, half-moon shape at the base of some nails (the lunula) is the visible edge of the matrix. On fingers where the lunula is larger, growth tends to be slightly faster, because a bigger matrix means more cell production.
Which Fingers Grow Fastest
Not all fingernails grow at the same speed. The middle finger on your dominant hand typically grows the fastest. It’s the longest finger, receives the most blood flow, and gets the most stimulation from everyday tasks like typing, gripping, and writing. The pinky nail, being the shortest and least active finger, grows the slowest. Nails on your dominant hand generally outpace those on your non-dominant hand for the same reason: more use means more blood circulation to the fingertips.
Growth Slows as You Age
Nail growth rate drops significantly over a lifetime. Research published in the Journal of Investigative Dermatology found that the rate of linear nail growth decreases by about 50% between youth and old age. The decline isn’t perfectly steady, either. There appear to be roughly 7-year cycles where growth slows gradually, followed by 7-year periods where the decline is steeper. Children and teenagers have the fastest-growing nails, while people over 60 often notice their nails growing noticeably slower and becoming thicker or more brittle.
This slowdown is tied to reduced blood circulation and slower cell turnover, both natural parts of aging. If you’re in your 20s, your nails are likely growing closer to 4 millimeters per month. By your 70s, that number may be closer to 2 millimeters.
Does Season or Climate Matter?
The effect of weather on nail growth is surprisingly small. In 1941, an American doctor named William Bennett Bean started measuring his own fingernail growth and continued for 35 years. He concluded that climate, season, and geographic location had no meaningful effect on growth rate. Other studies have found a slight uptick during summer months, likely because warm weather increases blood flow to the extremities.
If your nails seem to grow faster on vacation, the more likely explanation is that you’re not wearing them down as much. Less manual work and more time relaxing means less breakage, not faster production.
What Slows Nail Growth Down
Severe nutritional deficiency is one of the clearest ways nail growth gets disrupted. Protein deficiency, in particular, can dramatically slow growth and produce horizontal grooves or ridges across the nail plate (called Beau’s lines). These lines mark a period when the nail matrix temporarily slowed or paused its cell production due to illness, malnutrition, or severe stress. Chronic alcoholism, which often leads to poor nutrient absorption, is another common cause.
In extreme cases like severe malnutrition in children, nails become soft, thin, and fissured, with visibly impaired growth. For most people in developed countries, though, normal dietary variation has minimal impact on growth speed. Biotin supplements are widely marketed for nail growth, but they primarily help people who are actually biotin-deficient, which is uncommon.
Poor circulation from conditions like diabetes or peripheral artery disease can also slow nail growth, since the matrix depends on a steady blood supply to keep producing new cells. Smoking has a similar effect by constricting blood vessels in the extremities.
Putting the Numbers in Perspective
At 42 millimeters per year, your fingernails grow roughly as fast as the Antarctic ice sheet moves. It’s slow enough that you won’t notice daily changes, but fast enough that skipping a trim for a few weeks is obvious. If you never cut your fingernails for an entire year, you’d have about 1.7 inches of free edge extending past your fingertip, assuming none of them broke (which they almost certainly would).
Toenails, at their pace of about 0.8 inches per year, explain why ingrown toenails and fungal infections take so long to resolve. Any treatment that requires the damaged nail to grow out and be replaced by healthy nail demands patience measured in months, not weeks.