Fingernails grow about 3 to 3.5 mm per month, while toenails grow roughly half that speed at 1 to 1.6 mm per month. That means a full fingernail takes around 6 months to completely replace itself, and a toenail can take up to 18 months.
Fingernails vs. Toenails
The difference in speed between fingernails and toenails is striking. A large analysis found average fingernail growth of 3.47 mm per month compared to 1.62 mm per month for toenails. That’s more than twice as fast. The gap comes down to blood flow: your fingers receive significantly more circulation than your toes, and the cells that produce nail tissue (located just beneath the cuticle) divide faster when they get more blood supply and nutrients.
In practical terms, if you lose a fingernail entirely, expect about 6 months before it grows back fully. A lost toenail, particularly on the big toe, can take 12 to 18 months to return completely. These timelines assume healthy growth. Injury to the nail bed or the growth area under the cuticle can extend them considerably.
Not All Fingers Grow at the Same Speed
Your middle finger produces nail the fastest, and nails on your dominant hand outpace those on your non-dominant hand. The explanation is straightforward: longer fingers get better blood flow, and the hand you use more often experiences more physical stimulation throughout the day. That increased circulation and micro-trauma signals the nail-producing cells to keep dividing. Your pinky nail, by contrast, grows the slowest of all ten fingernails.
How Age Changes the Timeline
Nail growth speeds up throughout childhood and peaks sometime in your 20s or 30s. After that, the rate steadily declines. Over an entire lifespan, growth speed can drop by as much as 50%. So if you’re in your 70s, your nails are growing roughly half as fast as they did in your 30s. This is one reason older adults often notice their nails becoming thicker and more brittle: the nail plate spends more time exposed to the environment before it’s replaced.
Seasonal and Environmental Factors
Your nails grow slightly faster in summer than in winter. Warmer temperatures increase blood flow to your extremities, which feeds the nail matrix more nutrients and oxygen. If you’ve ever noticed your nails needing a trim more often during a beach vacation, it’s not your imagination. The effect is modest, but it’s been observed in multiple studies over the decades. Cold environments have the opposite effect, slowing circulation to the fingers and toes and reducing growth speed along with it.
What Slows Nail Growth Down
Beyond aging and cold weather, several health conditions and circumstances can measurably slow nail growth. Poor circulation from conditions affecting blood vessels in the extremities reduces the supply line to your nail matrix. Severe illness, major surgery, or high fever can temporarily halt growth altogether, leaving a horizontal groove across the nail called a Beau’s line. You can sometimes read these lines like a timeline, estimating when an illness occurred based on where the groove sits on the nail.
Chemotherapy is one of the most dramatic disruptors of nail growth. Because these treatments target rapidly dividing cells, nail-producing cells get caught in the crossfire. Nails may grow more slowly, develop ridges, become discolored, or in some cases detach from the nail bed during treatment.
Nutritional deficiencies can also play a role, though not always the ones people expect. Iron deficiency and thyroid disorders are among the more common culprits behind nails that grow slowly or break easily.
Do Biotin Supplements Help?
Biotin is heavily marketed for nail and hair growth, but the clinical evidence is thin. No studies have proven that biotin supplements change how fast nails grow or how they look in people who aren’t already deficient. Some people swear by it anecdotally, but biotin deficiency is rare in the U.S. and most developed countries. If your nails are growing slowly or breaking frequently, it’s more likely caused by another issue, such as low iron or an underactive thyroid, than a biotin shortage.
That said, topical treatments and certain oral medications have shown measurable effects in clinical settings. One small study found that a specific prescription medication increased nail growth speed by about 50%, but these are medical interventions rather than over-the-counter supplements. For most people, the best way to support healthy nail growth is maintaining good nutrition, staying hydrated, and protecting nails from repeated trauma or harsh chemicals.
A Quick Growth Reference
- Fingernails: 3 to 3.5 mm per month, full replacement in about 6 months
- Toenails: 1 to 1.6 mm per month, full replacement in 12 to 18 months
- Fastest finger: middle finger on your dominant hand
- Peak growth age: 20s to 30s, declining steadily after
- Fastest season: summer, due to increased blood flow