Beauty Calculators
Eyelash regrowth.
Eyelashes grow about 0.12 to 0.14 mm a day. Enter the current and full length for a range in weeks, or enter days since your last lash set to see the gap an extension fill has to close. Runs in your browser.
Your lashes
Regrowth time
Fill the form and press Calculate.
Worked example
A lash at 3 mm needs 6 mm to reach 9 mm. At 0.14 mm/day that is 43 days and at 0.12 mm/day 50 days, so about 6 to 7 weeks. An extension gap after 14 days is 14 x 0.12 to 14 x 0.14 = 1.7 to 2.0 mm, which is why fills are booked every 2 to 3 weeks.
How it works
Days to regrow = (full length - current length) / growth per day, shown for 0.14 mm/day (fast end) and 0.12 mm/day (slow end). The extension gap = days x growth per day, because the extension stays glued to the natural lash while the lash lengthens at the base.
What this is not. A lash that has fallen out has to enter a new growth phase first, so a bare lid takes longer to show anything. Lash cycles are staggered, which is why you lose a few every day and others are at different lengths. Lengthening serums, pulling and heavy extensions can all affect lashes. Persistent loss, redness, swelling or crusting of the lid deserves a doctor or optometrist, particularly if you wear extensions.
Sources and basis: Thibaut S, De Becker E, Bernard BA, et al., Human eyelash characterization, Br J Dermatol 2010;162(2):304-310 (growth about 0.12 to 0.14 mm/day, staggered cycles).
FAQ
How long do eyelashes take to grow back?
A lash that has reached the end of its life takes several weeks to restart, then roughly 6 to 8 weeks to reach full length at about 0.12 to 0.14 mm a day. A full lash set usually looks complete in about 2 to 3 months.
How fast do eyelashes grow in a day?
About 0.12 to 0.14 mm in the published measurements, roughly 1 mm a week.
How often should I get lash extension fills?
Most lash artists recommend every 2 to 3 weeks. After 14 days the natural lash has grown about 1.7 to 2 mm, so the extension sits visibly away from the lid.
Do lash serums make lashes grow faster?
Prescription bimatoprost can lengthen lashes, with side effects such as lid darkening and irritation. Cosmetic serums have less evidence. Speak to your doctor before using a prescription product.
Why am I losing lashes?
Losing a few each day is normal. Heavy loss, redness, itching or scaling can come from irritation, allergy to glue or mites and should be checked by a professional.
Disclaimer
Not medical advice. Growth rates are published averages. See a doctor or optometrist about lash loss, painful or swollen lids, or a reaction to extensions.