The short answer
On average, fingernails grow about 3.47 mm a month and toenails about 1.62 mm a month.1 So a mark on a fingernail takes roughly as many months to grow out as the millimeters it has left to travel, divided by 3.5. A whole fingernail can take 6 months or longer to regrow, and a toenail 12 to 18 months.2
Free, no signupEmbeddableSources checked October 2026
Got a white spot, a dent, a bruise, peeled-gel damage or a split you’re waiting to clip off? Or a nail that came off and you want to know when it’ll be back? Measure, pick your nail, and the calculator gives you a date. It works from the growth rates measured in a published study of healthy young adults, plus the regrowth times the American Academy of Dermatology gives.1,2
Nail grow-out calculator
Free edge = where the nail leaves the skin (the start of the white tip). Measure along the middle of the nail.
Estimate
The mark rides up toward the free edge as the nail grows. Once it passes the edge, you can trim it off.
Using it with a class or on your own site? Embed the calculator free with one line of code.
How to measure your nail
All you need is a ruler with millimeter marks and good light. Measure along the middle of the nail, from the cuticle line toward the tip. The study behind the growth rates measured the same way: from the skin fold at the base of the nail (the cuticle line) to a mark filed on the nail.1
- Find the cuticle lineWhere the skin at the base meets the nail. Every measurement starts here.
- Measure to the markLine the ruler up with the cuticle and read off where the spot, line or damage sits.
- Measure to the free edgeThe point where the nail leaves the skin and the white tip begins. That is where the mark has to reach.
Only have a ruler in inches? Switch the calculator to inches; it converts for you (1 inch is 25.4 mm).
How the calculator works
distance left (mm) ÷ growth rate (mm a month)Growth rate:
3.47 for fingernails, 1.62 for toenails1 · days = months × 30.44Take a white spot 3 mm above the cuticle on a fingernail whose free edge starts at 11 mm. It has 8 mm to travel. At 3.47 mm a month that is about 2.3 months, or 70 days. The same 8 mm on a toenail takes about 4.9 months (150 days), because toenails grow less than half as fast.1
The “how old is a mark” mode runs the same math backward: a mark 5 mm above the cuticle on a fingernail has been growing for about 1.4 months, so it sat at the cuticle line about six weeks earlier.
The “whole nail” mode doesn’t use the growth rate at all. A nail that has come off has to grow back from the base, so the calculator uses the regrowth times dermatologists give: 6 months or longer for a fingernail and 12 to 18 months for a toenail.2
Why your date may differ
- The rates are averages from 22 healthy young adults.1 Younger people, men and nail biters grew a little faster in that study, though the differences were not statistically significant.1
- The little fingernail grew slower than the other fingernails, and the big toenail faster than the other toenails.1 Right and left hands grew at about the same rate.1
- Children’s nails grow faster.2
- A fever, an injury, chemotherapy or major stress can slow or stop nail growth for a while.3
Nail growth in numbers
| What is growing out | Typical time |
|---|---|
| White spot on a fingernail | up to 6 to 9 months4 |
| White spot on a toenail | 12 to 18 months4 |
| Whole fingernail after it is removed | 6 months or longer2 |
| Whole toenail | 12 to 18 months2 |
| Nail after a fungal infection clears | a year or longer2 |
| Clear nail on the big toe after fungus treatment | a year or longer5 |
White spots caused by a knock or bite slowly grow out until you can clip them off.4 Those 2010 growth rates were also faster than estimates made decades earlier, so older charts tend to overstate how long nails take.1
When a mark isn’t just a mark
See a dermatologist if
- A dark streak is new or changing. The American Academy of Dermatology says a new or changing dark streak in a fingernail or toenail needs a skin cancer check.3 A bruise from an injury grows out with the nail; a streak that stays put or spreads is a reason to book.
- Deep grooves run across the nail and you can’t think why. They mean something slowed or stopped growth for a while.3 If there is no obvious cause, the AAD says to see a dermatologist or your primary care doctor.3
For the parts of the nail and what each one does, see our nail glossary. Parents can find trimming-by-age advice in our kids’ nail care guide, and salon clients can check what to look for in our nail salon safety guide.
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How to cite this calculator
Polished & Pretty Nails. (2026). Nail grow-out calculator: When will your nail grow out? https://polishedandprettynails.com/nail-growth-calculator/FAQ
Sources
Every number on this page was re-checked against its source on October 10, 2026.
- Yaemsiri S, Hou N, Slining MM, He K. Growth rate of human fingernails and toenails in healthy American young adults. J Eur Acad Dermatol Venereol. 2010;24(4):420-423 (PubMed abstract). https://pubmed.ncbi.nlm.nih.gov/19744178/
- American Academy of Dermatology, Nail fungus: Diagnosis and treatment. https://www.aad.org/public/diseases/a-z/nail-fungus-treatment
- American Academy of Dermatology, 12 nail changes a dermatologist should examine. https://www.aad.org/public/everyday-care/nail-care-secrets/basics/nail-changes-dermatologist-should-examine
- Cleveland Clinic, White Spots on Nails (Leukonychia). https://my.clevelandclinic.org/health/symptoms/25243-white-spots-on-nails
- American Academy of Dermatology, Nail fungus: Overview. https://www.aad.org/public/diseases/a-z/nail-fungus-overview
This calculator gives an average-based estimate for planning. It is not medical advice and can’t diagnose a nail problem. If a nail is painful, swollen, infected or changing in a way you can’t explain, see a dermatologist or your doctor.