Hair growth science: How fast does hair actually grow?

Here's how you can encourage growth.

Written by
Bailey Petts
Medically reviewed by
Last updated
April 29, 2024
min read
Hair growth science: How fast does hair actually grow?
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How much do you know about the hair growth cycle? Largely, people aren't across the intricacies of hair and how it grows.

Understanding this cycle and how best to look after your hair can make a huge impact on how much it grows over time. If you want to encourage hair growth and promote healthy hair, there are things you can do.

So, let's get into the natural growth cycle, and figure out: how long does hair take to grow?

How does hair grow?

A hair bulb creates the base of all hair follicles and in these hair bulbs, there are lots of new cells.

This collection of new cells sticks together in the hair bulb, becoming hard and a full strand of hair grows from a group of hardened cells. New hardened cells continue to attach to the hair from underneath and the hair is then slowly pushed out of the skin [1]. Hello, new hair.

Your hair growth is based on how many new, hardened cells are produced.

How fast does hair grow?

It's a big question: how long does hair take to grow? And, how long does it take for hair to grow back if you've noticed hair loss?

It is a relatively gradual process — although it may feel like your roots say otherwise. Didn't I just go to the hairdresser? But, for most people, it's at a rate of around 1cm each month.

It's important to note that the growth phase and the entire growth cycle can be impacted by the following things:

  • Age
  • Hair types
  • Health conditions
  • Hormones
  • Nutrition
  • Your general health [2]

The growth cycle for each strand of hair can be anywhere from 2-6 years. This seems like a huge variation, doesn't it? What we know from this, then, is that there are things that impact everyone's growth phase differently [3].

We're all born with about 100,000 hair follicles. And the above list can impact our hair follicles, sometimes stopping them from producing hair altogether which is when you'll notice thinning hair or bald patches.

How long will hair grow at different periods of time?

The hair growth rate is relatively slow and would be painstaking if we watched it on a daily basis [4].

But, the growth process is actually very interesting and is comprised of 4 phases:

  • The anagen phase (the anagen phase or growing phase is when the cells in your hair are dividing the quickest)
  • The catagen phase (transition phase)
  • The telogen phase (resting phase)

These 3 phases encompass the growth and change of the hair.

Then, the last stage:

  • The exogen phase (or final stage)

As this is the last stage of your hair's life, it will shed. And, unless you're experiencing baldness, new hair will be ready to take its place.

Each hair phase is as important as the other — the active growth phase, the transition phase and the resting phase have to do with the maturation of the hair strands while the final stage is just about making room for your new hair to come through.

As each phase lasts a different amount of time, depending on factors such as age or nutrition, there are things you can do to alter it. But, first, let's see how the hair follicle looks at various timelines [5].

  • Daily: The healthy hair growth rate per day is around 0.35mm
  • One week: Human hair will grow 2.45mm per week
  • One month: You can see about 0.5 inches of hair growth in a month
  • Over 3 months: Around 1.5 inches every 3 months
  • A year: Coming to 6 inches in a year

It might not sound like too much, but 6 inches can be the difference between short hair and long hair.

Ways to help support hair growth

There are ways to keep your hair healthy, revive damaged hair and improve your scalp health. In turn, you might notice that your hair growth rate either increases or that your hair is stronger and healthier.

Whether you're dealing with hair loss and are looking for growth treatments or you simply want to grow out a particular haircut, here are ways to support hair growth.

Hair loss treatment

While it's normal to lose about 100-150 strands of hair per day (in the exogen stage), hair loss means that something is preventing your hair from growing.

Male pattern baldness is particularly common among Cacasian men, affecting roughly 1 in 5 men in their 20s, 1 in 3 men in their 30s and nearly 1 in 2 men in their 40s [12]. And, hair loss can start as early as your 20s.

Pilot's personalised hair loss treatment can help you treat hair loss and promote healthy hair growth by improving the delivery of vital nutrients to the follicles, while also blocking the hormone which impacts hair growth.

While hair loss or breakage can be disheartening, it is treatable and the earlier you jump on it, the better. In fact, patients who began treatment between the ages of 20-40 experienced 60% more hair density compared to those who started between 41-60 [13].

Use growth hair care products

Consider swapping out your shampoo, conditioner and other hair care products for ones that are formulated to promote hair growth.

Pilot’s Hair Growth Booster Kit is a 4-step system designed to support healthy hair. It contains our Biotin Hair Gummies, which are packed with biotin to help support the synthesis of kertin and our Hair Growth Shampoo & Conditioner, which contains active ingredients like biotin, saw palmetto and caffeine to target thinning hair, minimise breakage and give your follicles the best chance to thrive.

Rounding out the kit is the Derma Roller, which contains hundred of tiny needles so you can enjoy the benefits of microneedling from home.

By gently rolling the Derma Roller over your scalp, these tiny needles rupture the outer layer of the dermis, creating blood flow to the area, and triggering a healing reaction in the scalp. By activating the scalp’s stem cells, surrounding follicles are stimulated, resulting in hair growth.

Get regular trims

Regular trims and haircuts can help you maintain your hair. By cutting the ends off, you're avoiding split ends, which can cause hair breakage.

Many people are scared to trim their hair if they want it to be longer, but if you make sure that you're regularly refreshing the dry ends, you'll have fuller-looking hair that's healthier.

Avoid too many treatments

For colour-treated hair, it can be hard to grow hair to the length you want. Why? Well, dyeing your hair too frequently can irritate your scalp, create brittle hair and in turn, encourage more hair fall.

In other cases, you might be using one too many hair products that aren't great for your hair health. It's important to be aware of what you're using as some products can contain harsh ingredients that strip the hair of its natural oils, making it more fragile and prone to breakage.

Keratin supplements

Your hair is made up of keratin and dead skin cells, so it makes sense that keratin supplementation would have a positive impact on your hair's health.

While more research is needed to confirm this, one study from 2018 did find that it helped increase hair diameter and decrease hair loss [7].

Reduce stress

Stress can be a trigger of hair loss for many people [9]. Stress can manifest in the following 3 types of hair loss:

  • Telogen effluvium: Hair follicles are pushed into the resting phase, meaning they're more likely to fall out
  • Trichotillomania: A mental health disorder that involves urges to pull out hair from the scalp, eyelashes, eyebrows and other areas
  • Alopecia areata: Your body's immune system starts attacking your hair follicles, resulting in hair loss

Eat a healthy and balanced diet

Nutrition is important for many aspects of your well-being, including your hair [10]. Ensure you're eating enough protein and trace minerals such as magnesium, iron and biotin for the health of your hair.

Nutritional deficiency may impact hair growth and hair structure, so a varied and balanced diet will make sure you're consuming all the right vitamins, macronutrients and minerals for a healthy dome.

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