Hair Growth Calculator
Calculate how many months it takes to grow your hair to a target length.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Hair Growth Calculator
Calculate your hair growth timeline in two steps:
- Measure your current hair length. Measure from the root at your scalp to the tip of your hair. For curly hair, measure a stretched strand, not the curl.
- Enter your target length. Type the length you are aiming for. The calculator shows months and years to reach that length at the average growth rate.
The calculator uses the average human hair growth rate of 0.5 inches per month (6 inches per year). Individual growth rates can range from 0.3 to 0.6 inches per month depending on genetics, health, and other factors.
About Hair Growth
Human hair grows in cycles consisting of an anagen (growth) phase, catagen (transition) phase, and telogen (resting/shedding) phase. The anagen phase typically lasts 2-6 years, during which hair grows about 0.5 inches per month on average. Genetics determine how long your anagen phase lasts, which directly affects your maximum potential hair length.
Diet, stress, hormones, and hair care practices can all influence growth rate and hair health. Protein intake (hair is primarily keratin), iron levels, and scalp health are particularly important. Trimming split ends does not make hair grow faster, but it prevents breakage from splitting up the shaft, which helps retain length.
Frequently Asked Questions
How fast does hair grow per month?
The average human hair grows about 0.5 inches (1.27 cm) per month, which equals 6 inches (15 cm) per year. Individual rates vary from about 0.3 to 0.6 inches per month. Scalp hair grows faster than eyebrows and body hair. Growth rate also varies by race, with Asian hair typically growing slightly faster than European or African hair on average.
What can I do to grow hair faster?
While genetics set the upper limit, several factors support healthy growth: adequate protein intake (hair is 91% protein), sufficient iron and biotin, stress management, and scalp health. Scalp massages may modestly increase growth by stimulating blood flow. Avoiding excessive heat styling, chemical treatments, and tight hairstyles prevents breakage that makes hair appear to grow slower than it actually is. No supplement or topical product dramatically increases growth rate beyond genetic limits.
How long does it take to grow hair from short to shoulder length?
Shoulder-length hair is approximately 12-14 inches long. Growing from a short cut of about 2 inches to shoulder length requires about 10-12 inches of growth, which takes roughly 20-24 months at average growth rates. Adding regular trims to maintain healthy ends will slow length progression slightly. Protective styles that reduce mechanical damage can help retain more of the length your hair grows.
Does hair grow faster in summer?
There is some evidence that hair grows slightly faster in warmer months, possibly due to increased blood circulation to the scalp or longer daylight hours affecting hormone levels. However, the effect is modest, estimated at 10-15% faster growth in summer versus winter. This would mean a difference of only a fraction of an inch per month. Seasonal variation in growth rate is much smaller than variation between individuals.