Beauty Calculators
Nail growth.
Fingernails grow about 3.5 mm a month and toenails about 1.6 mm. Enter your current and goal length to get a timeline and a date, or find out when the gap at your cuticle will need a fill. Runs in your browser.
Your nails
Timeline
Fill the form and press Calculate.
Worked example
Fingernails grow about 3.47 mm per month, which is 3.47 / 30.4375 = 0.114 mm a day. From a 2 mm free edge to an 8 mm goal is 6 mm: 6 / 0.114 = 53 days, about 7.5 weeks. A gel or acrylic fill gap of 2 mm shows after 2 / 0.114 = about 17.5 days, which is why fills land every 2 to 3 weeks.
How it works
Growth in mm/day = monthly rate / 30.4375. Days to goal = (goal - current) / growth per day. The default rates are the averages measured by Yaemsiri and colleagues in 2010 in healthy American adults: 3.47 mm/month for fingernails and 1.62 mm/month for toenails.
What this is not. It is an average. Nails grow faster in summer, in younger adults, on the dominant hand and on longer fingers, and slower with age, illness or some medicines. Breakage, filing and rounding mean visible length can grow slower than the nail does. Nail thickness changes, ridges or colour changes are worth showing to a doctor.
Sources and basis: Yaemsiri S, Hou N, Slade MD, et al., Growth rate of human fingernails and toenails in healthy American adults, J Am Acad Dermatol 2010;63(4):607-614 (fingernails 3.47 mm/month, toenails 1.62 mm/month).
FAQ
How long does it take for fingernails to grow?
On average about 3.5 mm a month, so a typical nail takes about 4 to 6 months to grow from base to tip. Going from short to a 10 mm free edge takes a couple of months.
How fast do toenails grow?
About 1.6 mm a month on average, less than half the rate of fingernails. A full toenail takes 12 to 18 months to replace.
How often should I get a gel or acrylic fill?
Most salons recommend every 2 to 3 weeks. At average growth the gap at the cuticle is about 2 mm after 17 days and 3 mm after about 26.
Do nails grow faster with biotin or supplements?
Evidence is limited. Biotin has helped people with brittle nails in small studies, but there is no strong evidence that it speeds growth in healthy people.
Why do my nails seem to grow slower than this?
Breakage and peeling trim length as it forms. Keep nails moisturised, file in one direction and avoid using them as tools.
Disclaimer
Not medical advice. Averages from one published study; your own nails may differ. See a doctor about sudden changes in nail growth, colour, shape or thickness.