How to use the nail regrowth time calculator
Choose fingernail or toenail, then enter the length of nail to replace in inches, the growth rate in inches per month and a start date. Leave the rate blank to use the average. Decimals such as 0.04 inch work fine; the page converts to millimeters internally, rounds the required days up, converts them to months and weeks, and gives the expected finish date. One month converts to 30.4 days and one week to seven, and the conversion is printed with the result.
Average growth rates and full replacement time
In a study of healthy adults (Yaemsiri et al., 2010), fingernails grew an average of about 3.47 mm (roughly 0.14 inch) per month and toenails about 1.62 mm (roughly 0.06 inch) per month. A whole fingernail takes about 6 months to replace and a toenail about 12 to 18 months (as of October 2026). Rates vary with age, season and health, so for a closer estimate mark the nail near the tip, measure how far the mark has traveled a few weeks later and enter your own monthly rate.
This page only converts length and rate into time. It does not grade discoloration or thickening, and it does not decide whether a fungal infection is present or how far it has progressed. There are no published weights for turning color or thickness into a score or a stage, and an unfounded score delays care when it reads low. Pain, a changing shape or color, or spreading beyond one nail are reasons to be seen. A short figure here does not mean nothing is wrong.
Frequently Asked Questions
Leave it blank and the page uses the average. In a study of healthy adults (Yaemsiri et al., 2010), fingernails grew an average of about 3.47 mm (roughly 0.14 inch) a month and toenails about 1.62 mm (roughly 0.06 inch). For your own rate, mark the nail near the tip, measure how far the mark moves over a few weeks and scale it to a month.
A whole fingernail usually takes about 6 months to grow out and a toenail about 12 to 18 months (American Academy of Dermatology and others). Toenails grow at roughly half the speed of fingernails, so the same length takes about twice as long.
There is no published rule for grading stages from color or thickness, so the page does not judge them. If color or shape is changing, get it looked at rather than converted into a number.