Hair grows on average 1 centimetre (about 0.4 inches) per month, or roughly 12 cm (about 4.7 inches) a year. This rate varies from 0.8 to 1.25 cm depending on genetics, age, the season and your overall health. Each hair goes through a three-phase cycle: growth (anagen), transition (catagen) and rest (telogen).
| Time | Average growth |
|---|---|
| 1 month | about 1 cm (0.4 in) |
| 3 months | about 3 cm (1.2 in) |
| 6 months | about 6 cm (2.4 in) |
| 1 year | about 12 cm (4.7 in) |
So how fast does hair grow per month, exactly? The one-centimetre figure is an average seen in dermatology studies, but it hides big differences between individuals. Some people gain barely 8 mm a month, others more than 1.2 cm. To understand why, you first need to understand how a hair's life cycle works.
The hair growth cycle: the 3 phases of a hair's life
Each hair follicle works independently and goes through a cycle made up of three distinct phases. This out-of-sync pattern is why we don't lose all our hair at once, unlike some animals that moult.
| Phase | Duration | Share of hairs | What happens |
|---|---|---|---|
| Anagen (growth) | 2 to 7 years | 85 to 90% | The hair actively grows by about 1 cm/month |
| Catagen (transition) | 2 to 3 weeks | 1 to 2% | The follicle shrinks and growth stops |
| Telogen (rest) | about 3 months | 10 to 15% | The hair stays in place, then falls out and a new one replaces it |
The anagen phase: active growth
This is the longest and most important phase. For 2 to 7 years, the cells of the follicle matrix divide rapidly and produce the hair fibre. The length of this phase, largely determined by genetics, sets the maximum length your hair can reach: a 2-year anagen phase limits length to about 25-30 cm, while a 6-7 year phase allows very long hair.
The catagen phase: the transition
Short and discreet, this 2 to 3-week phase marks the end of production. The follicle shrinks back towards the surface of the scalp and the hair gradually detaches from its source of nutrients.
The telogen phase: rest and shedding
The "dead" hair stays attached for about 3 months before falling out, often pushed out by the new hair starting its own cycle. Losing 50 to 100 hairs a day is therefore perfectly normal: these are simply the hairs that have reached the end of the telogen phase.
How much your hair grows per month: the factors at play
Genetics
This is the number one factor. It determines both the growth rate and the length of the anagen phase. Studies also point to differences by hair type: Asian hair grows slightly faster on average (about 1.3 cm/month) than Caucasian hair (about 1.2 cm/month) and Afro-textured hair (about 0.9 cm/month), which is also more prone to breakage because of its elliptical structure.
Age
Growth peaks between the ages of 15 and 30, then gradually slows down. With age, anagen phases get shorter and some follicles produce finer hair.
The season
Several clinical observations suggest slightly faster growth in summer, probably linked to increased blood circulation in the heat, and more noticeable seasonal shedding in autumn, when more hairs enter the telogen phase at the same time.
Diet
Hair is made of more than 90% keratin, a protein. Not getting enough protein, iron, zinc or B vitamins can slow growth and weaken the hair fibre. Iron deficiency, which is common in women, is regularly linked in the dermatology literature to diffuse hair loss.
Hormones
Oestrogens extend the anagen phase — which is why many women notice thicker hair during pregnancy, followed by catch-up shedding after giving birth. Conversely, androgens (DHT) can shorten the cycle in people who are predisposed. Chronic stress and some thyroid disorders can also disrupt the cycle. If in doubt, seeing a doctor is still the best approach.
Hair growth myths, debunked
- "Cutting your hair makes it grow faster." False. Growth happens at the root, in the follicle; scissors only affect the ends. Regular trims do, however, get rid of split ends and limit breakage, which helps you keep the length you have gained — hence the impression of faster growth.
- "Brushing 100 times a day stimulates growth." False. Excessive brushing mostly creates friction and breakage. Gentle daily brushing is enough to spread the sebum.
- "Hair grows faster at night / during a full moon." No scientific data supports these beliefs. Growth is continuous, day and night.
- "Frequent shampooing slows hair growth." False. Washing doesn't reach the follicle. A clean scalp is actually a more favourable environment.
- "Grey hairs grow back faster when you pull them out." Pulling out one hair won't make three grow back: each follicle only produces one hair at a time. Repeated pulling can, however, damage the follicle.
How to measure your hair growth properly
To find out whether your hair is growing at a normal rate, you can use two simple, complementary methods at home.
The photo method
- Take a photo of your back, with your hair smoothed or relaxed, in the same position, with the same lighting and the same reference garment (a seam, a print).
- Repeat the photo every month, on a fixed date.
- Compare where your ends sit against the reference on the garment. Over 3 months, the change becomes clearly visible.
The marker strand method
- Separate a small strand, always in the same place (for example behind the ear).
- Measure it from root to tip with a soft tape measure, holding the hair taut.
- Write down the measurement and repeat every month, in exactly the same place.
- On curly or coily hair, always measure the hair stretched out: natural shrinkage can hide several centimetres of real growth.
To estimate how long it will take to reach a target length based on your growth rate, you can use a free hair growth calculator.
Can you make your hair grow faster?
Let's be honest: you can't radically change a growth rate dictated by genetics. What you can do is make sure your follicles work in the best possible conditions: a diet with enough protein and iron, regular sleep, stress management, scalp massage (which stimulates local microcirculation according to several small studies), and limiting the damage that breaks off the length you have gained (excessive heat, repeated bleaching, very tight hairstyles).
Some topical actives are also being researched for their ability to support the anagen phase. For a complete overview of the available solutions and how strong the evidence is, read our complete guide to hair growth serums.
Key takeaways
- Average growth is about 1 cm per month (0.8 to 1.25 cm depending on the person).
- The hair cycle has three phases: anagen (2-7 years), catagen (2-3 weeks), telogen (3 months).
- The length of the anagen phase, which is genetically determined, sets your maximum length.
- Losing 50 to 100 hairs a day is normal.
- Cutting your hair doesn't make it grow faster, but it helps you keep your length.
- The photo method and the marker strand let you track your growth objectively.
If you would like to add a targeted scalp treatment to your hair routine, discover the ORVOVA roll-on hair serum.
