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Home arrow Beauty arrow Hair arrow How Long Does It Take for Hair to Grow? Understand the Hair Growth Process

How Long Does It Take for Hair to Grow? Understand the Hair Growth Process

Written by Rosmy Barrios, MD
Fact checked by Edna Skopljak, MD
Last update: May 10, 2023
8 min read 1009 Views 0 Comments
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Ever wished your hair would grow faster? Understand the hair growth process to see what you can do to stimulate growth.

how long does it take for hair to grow

At some point in time, most of us have felt frustrated with how slowly our hair seemed to grow. Bad haircuts, stubborn hairstyles, and post-pregnancy hair loss make all of us wonder how long it takes for the hair to grow and what could speed up the process. 

And yet, hair growth is a complex process influenced by various factors such as genetics, diet, age, and overall health.

Keep on reading to understand the hair growth process and learn the factors contributing to healthy hair.

How Long Does It Take for Hair to Grow?

Although the growth rate varies among people, on average, hair grows about half an inch per month or roughly 6 inches per year.

Mind that different parts of the body may have different growth rates. For example, hair on the scalp tends to grow faster than on the arms or legs.

The Science Behind Hair Growth

Hair growth is a complex process that is regulated by a variety of biological factors. To understand it, it’s necessary to explore the natural growth cycle

#1 How hair growth happens

Each hair on the human body grows from a special skin structure called hair follicles. There are over a million hair follicles on the scalp. Each hair follicle contains a bulb at its base that produces new hair cells.

Hair does not grow continuously. It grows in so-called hair growth cycles that consist of three phases: anagen (growth phase), catagen (transition phase), and telogen (resting phase). 

  • Anagen phase: The hair follicle produces new cells, which lengthens the hair. 
  • Catagen phase: The hair follicle transitions into a resting phase. The hair growth slows down. 
  • Telogen phase: The hair follicle is inactive. The body is preparing to shed hair, making way for new hair growth.

The final phase (although it does not belong to growth phases) is often separated in literature as the exogen phase – when the hair falls out. Because of this phase, you lose around 100 hairs daily.

#2 How long does it take to grow 3, 6, or 12 inches of hair?

Considering that hair grows an average of half an inch a month, the figures would be the following:

  • It would take half a year (6 months) for your body to grow 3 inches of hair.
  • It would take a year (12 months) for 6 inches of hair.
  • It would take 2 years (24 months) for 12 inches of hair.

Keep in mind, however, that individual growth rates can range from as little as 0.1 inch per month to several inches per year.

When it comes to other body parts (like armpits, legs, or arms), the hair growth cycle is shorter – it lasts for about a month. That explains why body hair is shorter than scalp hair. 

How Long Does It Take for Hair to Grow Back?

Haircut regret, waxing, thinned eyebrows, or more severe conditions (like hair loss after an illness) make people wish for hair to regrow sooner. Yet, not only a body part defines the hair growth rate – the cause of hair loss, too.

#1 After a haircut 

The time it takes for the hair to grow back after a haircut depends on several external and internal factors, from age and genetics to the length of the haircut and harsh hair treatments.

Apart from these factors, take an average growth speed of half-inch per month as a reference when counting hair growth after a haircut. 

#2 After hair loss 

The rate of hair growth after hair loss depends largely on the underlying cause or condition. 

In cases of more significant hair loss due to conditions such as alopecia areata or chemotherapy, the time it takes for the hair to grow back can be longer. 

Hair regrowth typically begins within one to six months after the hair loss, but it can take up to a year or more for the hair to fully regrow.

#3 After waxing or shaving

When you wax, you remove an entire hair root from the follicle. Therefore, it might take several weeks for the hair to fully regrow to its previous length. 

Shaving, on the other hand, removes only the top part of the hair above the skin’s surface. It will start regrowing immediately, so you might feel your hair again within two or three days.  

8 Main Factors That Influence Hair Growth

The rate at which hair grows can vary depending on many factors, including age, genetics, overall health, and the specific location of the body where the hair is growing. 

Also, such external factors as diet, stress, and certain medications or medical conditions play a role. 

#1 Age 

Hair growth slows down with age, and the hair becomes thinner and less dense. This is because the hair follicles shrink over time or they stop working. 

Human hair grows fastest when a person is between 15 and 30 years old and reduces its speed at age 40 to 50. 

Some women experience hair loss due to hormonal fluctuations in the body (menopause, post-pregnancy, polycystic ovaries, etc.).

#2 Sex

Men typically have more hair and faster hair growth than women, mainly due to differences in hormone production. Androgens, such as testosterone, play a crucial role in promoting hair growth in men. 

Women, contrarily, have higher levels of estrogen, which can help protect hair follicles from damage.

#3 Diet 

Follicle cells require specific nutrients to support hair health. When people mainly eat junk or processed food and exhaust themselves with intense work schedules, they deprive their bodies of essential nutrients. 

Hair is made up of protein, so consuming enough protein, minerals, and vitamins is crucial for hair health. Include such vitamins and minerals as iron, biotin, and vitamin D into your diet, and drink enough water.  

#4 Hair growth cycle 

The hair growth cycle differs from person to person. When an individual ages, the natural growth cycle becomes shorter.

Besides, many factors like illness, hormonal changes, or medications can disrupt the cycle, influencing the speed of hair growth. 

#5 Stress 

Chronic stress can disrupt the normal hair growth cycle and lead to stress-related hair loss. 

The process of losing hair due to stress is called telogen effluvium. It happens when stress makes the follicles enter the telogen (falling out) stage sooner.

After a significant stressor, up to 70% of hair in the anagen (active growth) stage suddenly enters the telogen phase, making your hair come out in handfuls.

Additionally, stress can negatively affect hair growth indirectly. Stressed people tend to engage in behaviors that can damage hair, such as pulling on hair or using heat-styling tools excessively.

#6 Vitamins

Vitamins are a building material for healthy hair. It is essential you consume enough vitamin A because it is linked to scalp skin and hair health.  

Vitamin C is crucial for collagen production and essential for healthy hair growth. Also, enrich your diet with vitamin D to promote hair follicle health. Lastly, consume vitamin E (an antioxidant) to prevent oxidative stress, which can damage hair.

#7 Hair and scalp health

The health of the hair and scalp is crucial for quickly growing hair. Conditions like dandruff, psoriasis, and scalp infections can inhibit hair growth. 

Besides, using harsh hair products or frequently styling hair can damage it and lead to breakage. Invest in good quality haircare products.

#8 Sleep

A good night’s sleep is essential for the body to repair and regenerate. During sleep, the body produces melatonin, which promotes healthy hair growth.

How to Speed Up Hair Growth

While you cannot make hair grow overnight (regardless of how frustrating it sometimes feels), there are things you can do to make your hair grow faster.  

  • Eat a healthy, nutrient-rich diet: A balanced diet rich in protein, vitamins, and minerals is crucial for healthy hair. Pick foods high in protein, omega-3 fatty acids, iron, folic acid, and vitamins D, C, and A. 
  • Hydrate yourself: Drink around 2 liters of water every day.
  • Get enough sleep: Aim for 7–8 hours each night to ensure your body has enough time to repair and regenerate.
  • Style hair moderately: Avoid using heat styling tools (like hair dryers and straighteners) too frequently. Opt for air-drying your hair instead. Avoid wearing tight hairstyles (like ponytails).
  • Massage your scalp: Massaging your scalp can help increase blood flow to the follicles, remove dead skin cells, and keep your hair healthy. Use your fingertips to gently massage your scalp in circular motions for a few minutes each time you wash your hair. 
  • Trim your hair regularly: Trimming hair every two months makes you get rid of split ends. While it won’t stimulate hair growth, your hair will look healthier and longer. 
  • Protect your hair from environmental damage: Use serums or oils to protect your hair from getting fizzy. If you style your hair with heat, use heat protection. Lastly, wear a hat during hot summer days to protect your hair from sun exposure. 
  • Manage stress: Find ways to manage stress, such as through exercise or meditation. It can help you sleep and feel better and make your hair grow faster.


Can hair grow back after going bald?

If the follicle has disappeared or has not produced new hair within the last few years, there is little chance it can grow back. If the follicle is still alive, you could grow hair back. Consult with a trichologist.

Can hair grow 1 inch a month?

Although the average rate of hair growth is half an inch per month, some people can grow 1 inch of hair per month.

How long will hair grow in 6 months?

You should expect your hair to grow about three inches in 6 months.

A Word From a Trichologist

Hair growth is a complex process affected by a variety of factors. While genetics play a significant role in determining the length and thickness of hair, you can still manipulate factors like diet, stress, and scalp health to promote hair growth.

Of course, don’t forget that hair growth is a slow process, and it can take several months to see noticeable results.

Change your daily eating, sleeping, and stress-management habits to see if that works. If a healthier lifestyle doesn’t make your hair grow faster, visit a trichologist.

A specialist can help identify any underlying issues with your hair health that may be slowing down the growth process. In most cases, if patients follow a customized treatment plan to regrow hair, they soon enjoy longer and healthier-looking locks.


On average, hair grows at a rate of half an inch per month. Many internal and external factors affect this process, from age and sex to harsh hair styling practices and chronic stress. 

It is possible to support hair growth and enjoy longer, fuller-looking, and healthier hair by following a balanced diet, managing stress levels, and avoiding heated hair styling tools.

If you start to lose hair excessively, consult a trichologist to find a solution to regrow your hair before it is too late. 

Written by Rosmy Barrios, MD
Dr. Rosmy Barrios, MD, is a medical advisor for the Health Reporter, the head of the anti-aging department, and a regenerative medicine specialist in several medical institutions with years of experience in aesthetic medicine and cosmetology.
The article was fact checked by Edna Skopljak, MD
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