Anagen Phase of Hair Growth: How Long Hair Can Get
The anagen phase of hair growth is the active growing stage of the hair cycle, and it is the single thing that decides how long your hair can ever get. Follicle cells divide, the strand pushes upward at roughly 1 to 1.5 cm a month, and the phase runs for anywhere between two and seven years depending mostly on your genetics. About 85 to 90 per cent of your scalp hair is in it right now.
Key takeaways
- Anagen length sets your maximum hair length. Two years of anagen gives roughly 30 cm, seven years gives well past the waist.
- Growth rate is fairly fixed at about 1 to 1.5 cm a month. Nothing on a shelf speeds that up.
- You cannot lengthen anagen with a cosmetic, but illness, crash dieting, low iron and severe stress can all cut it short.
- Most people are limited by breakage, not by growth. Hair reaches its length and then snaps off at the ends.
- Different body sites have wildly different anagen lengths, which is why eyebrows stay short and scalp hair does not.
- Shedding 50 to 100 hairs a day is the cycle working normally, not a warning sign.
What happens during the anagen phase of hair growth?
During the anagen phase of hair growth, cells in the hair matrix at the base of the follicle divide faster than almost any other cells in the body, and they push a continuously forming keratin strand up and out of the scalp. The follicle is at its deepest and most active, it is fed by its own blood supply through the dermal papilla, and the pigment cells sitting alongside colour the strand as it forms.
Everything above the skin is already dead by the time you see it. That single fact explains most of what follows on this page. You cannot feed, repair or revive the visible hair, because it is a keratin fibre with no metabolism. Everything you do that genuinely affects growth happens at the follicle, and everything you do to the length is damage limitation.
Anagen is one of four stages. If you want the full picture of what follows it, our hair growth cycle diagram walks through catagen, telogen and exogen with the timings.
How long does the anagen phase of hair growth last?
Scalp anagen runs about two to seven years in most people, and the number is largely inherited. That range is the whole reason some people can grow hair to their waist and others find it never passes their shoulders no matter what they buy. It is not a measure of hair health and it is not something you did wrong.
The arithmetic is worth doing once, because it settles a lot of arguments.
| Anagen duration | Growth at 1.25 cm a month | Roughly where that reaches |
|---|---|---|
| 2 years | 30 cm | Collarbone |
| 4 years | 60 cm | Mid back |
| 6 years | 90 cm | Waist and beyond |
Two caveats stop that table being a promise. Growth rate varies between people and slows a little with age, and almost nobody keeps every centimetre, because the oldest ends have been exposed to years of washing, brushing, heat and sun by the time they get there.
Why does eyebrow hair stay short?
Eyebrow and eyelash follicles have a very short anagen, measured in weeks rather than years, which caps their length before they ever reach nuisance size. Body hair sits in between. This is the clearest everyday demonstration that anagen length, not growth rate, controls final length, since a scalp follicle and an eyebrow follicle grow at broadly similar speeds.
It is also the reason a plucked eyebrow returns within weeks while a badly cut fringe takes months. The eyebrow follicle simply has a short cycle to restart.
What shortens the anagen phase of hair growth?
Anything that puts real strain on the body can push follicles out of anagen early and into resting, and the result is a diffuse shed two to three months later. That delay is why people almost never connect the shed to what caused it. The usual culprits are consistent.
- Illness with a high fever, surgery, or general anaesthetic. A classic trigger, and typically self-limiting over six to nine months.
- Rapid weight loss and very low calorie dieting. Hair is metabolically expensive and it is one of the first things the body deprioritises.
- Low iron, and specifically low ferritin. Common in anyone with heavy periods, and easily missed if only a full blood count is checked.
- Thyroid running fast or slow. Both affect cycling across the whole head rather than in a pattern.
- Childbirth. Oestrogen holds follicles in anagen through pregnancy, and the drop afterwards releases them together.
- Sustained severe stress. Not a bad week. Months of it.
This kind of shedding is telogen effluvium, and it is a different problem from androgen-driven miniaturisation, where anagen shortens a little more with every cycle and the hair gets progressively finer in a pattern. Our guide to how much shedding is too much covers how to tell them apart.
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Growth, shedding and breakage are three different things
| Problem | Where it happens | What you notice | What changes it |
|---|---|---|---|
| Hair loss | The follicle miniaturises | Wider parting or receding temples, in a pattern, over years | Hormones and genetics. A GP conversation |
| Hair shedding | Anagen ends early across the head | Handfuls at once, no pattern, starting 2 to 3 months after a trigger | Removing the trigger. It usually settles |
| Hair breakage | The fibre, above the skin | Short snapped pieces, rough ends, hair that will not pass a certain length | Heat, handling and conditioning. This is the fixable one |
Most people who feel their hair stopped growing are in the third row, not the first. The follicle is producing hair at the same rate it always did, and the ends are snapping off at roughly the same rate, so length stalls. That is a fibre problem, and it responds to changes you can make this week.
Can you make the anagen phase of hair growth last longer?
Not with a cosmetic, and anyone claiming otherwise is overstating what a shampoo can do. What you can do is remove the things that cut anagen short, which is a genuinely useful goal even though it is a less exciting sentence.
- Eat enough, and enough protein. Hair is keratin. Persistent under-eating shows up in the hair before almost anywhere else.
- Get iron checked if you have any reason to suspect it. Ask for ferritin specifically, not just haemoglobin.
- Get thyroid checked if you have other symptoms. Cold, fatigue, weight change, dry skin.
- Do not crash diet. A steady deficit is fine. Very low calorie plans are not, at least where hair is concerned.
- Look after the scalp. It is the environment the follicle sits in, and build-up, irritation and flaking are worth sorting out rather than tolerating.
Supplements only help if you were short of something to begin with. Taking extra of a nutrient you already have plenty of does nothing at the follicle, and very high dose biotin can interfere with some blood test results, so mention what you take before bloods are drawn. Our honest review of what hair vitamins actually do goes through it properly.
How do you keep the length that anagen gives you?
Keeping length is a breakage problem, and it is the half of this that is genuinely in your control. A hair that has been growing for four years has survived roughly 200 washes, 1,400 brushings and every heat tool you own, so the oldest 15 cm are always the most fragile part of your head.
- Detangle from the ends upward with a wide tooth comb, never from the roots down.
- Be gentle when wet. Wet hair stretches and snaps far more easily than dry hair.
- Condition the mid-lengths and ends every single wash. Slip is what stops mechanical snapping.
- Use heat protection, and turn the temperature down. Thermal damage is cumulative and permanent along the fibre.
- Trim little and often. A split travels upward. Removing 1 cm twice a year keeps more length than removing 8 cm once.
- Protect it overnight. A silk or satin pillowcase, or loosely tying hair up, cuts a surprising amount of friction.
Our full guide to what causes hair damage covers the fibre science, and how to prevent split ends covers the trimming question in detail.
What we make, and what it is honestly for
Our products are cosmetics. They support a healthy scalp environment and reduce breakage so hair looks fuller and can keep more of the length anagen gives it. They do not extend the growth phase and they are not medicines.
Condition Me® Hair Growth Conditioner, £13.95
The one that matters most if length is your goal. Cholesterol, shea butter and hydrolysed lupine protein add slip to the mid-lengths and ends, and hair that detangles easily is hair that snaps less.
Masque Me® Hair Growth Mask, £24.95
A weekly deep conditioner for the oldest 15 cm, which have taken years of washing and heat. Rosemary, provitamin B5, argan oil and hydrolysed lupine protein. It will not extend anagen, and it does help you keep what anagen gave you.
Protect Me® Heat Protection Spray, £13.95
Protection to 230°C. Heat damage along the fibre is cumulative and does not repair itself, so if you use a dryer or straighteners this is the cheapest way to hold on to length.
Frequently asked questions
How fast does hair actually grow?
About 1 to 1.5 cm a month on the scalp, or roughly 15 cm a year, which works out at a little over a centimetre while you read a long article. Rate varies between individuals, tends to be slightly faster in warm weather and slightly slower with age, and it is not something a product changes. Anyone promising accelerated growth is describing the same centimetre a month with better marketing.
Does trimming make hair grow faster?
No. Trimming happens at the end of the strand and growth happens at the follicle, so the two never meet. Trimming does help you keep length, because it removes splits before they travel up the shaft and cost you far more than the trim would have. Growth speed is unchanged, retained length improves.
Why has my hair stopped growing past my shoulders?
Almost always one of two reasons. Either your anagen phase is on the shorter end, which is genetic and sets a ceiling, or your hair is reaching that length and then breaking off at the same rate it grows, which is a fibre problem. Check the ends: if they are rough, split and uneven, it is breakage and it is fixable.
Is 100 hairs a day too many?
No. Fifty to a hundred a day is the normal end of the cycle doing its job, and it looks like more than it is when it collects in the shower. What matters is a sustained change: two to three hundred a day for weeks, or a noticeably thinner ponytail, is worth investigating.
Does scalp massage help hair grow?
The evidence is limited and the effect, if any, is modest. Massage is pleasant, it costs nothing, and it gets you handling your scalp regularly so you notice changes early. Treating it as a nice habit rather than as a growth method is the honest framing.
Do hair growth shampoos extend the growing phase?
A shampoo is on the scalp for a minute or two and then rinsed away, so no cosmetic can claim to lengthen anagen. What a good one does is clean the scalp without stripping it and leave hair less prone to snapping, which protects the length you already grew. Judge one on that, not on a growth promise.
Does hair grow faster in summer?
Slightly, in most studies, and the difference is small enough that you will not notice it without measuring. Warmer temperatures and better circulation to the skin are the likely explanations. Seasonal shedding in autumn is the more noticeable seasonal effect and it is also normal.
Does shaving make hair grow back thicker?
No. Shaving cuts the fibre at its widest point, so the new growth feels blunt and coarse for a while, and that is a texture illusion rather than a change in thickness. The follicle is entirely unaffected by anything happening above the skin.
Sources and references
- StatPearls, NCBI Bookshelf: Physiology, Hair
- StatPearls, NCBI Bookshelf: Telogen Effluvium
- StatPearls, NCBI Bookshelf: Androgenetic Alopecia
- NHS: Hair loss
- NHS: Iron, how much you need and food sources
The short version
The anagen phase of hair growth runs two to seven years, adds about 1.25 cm a month, and sets the ceiling on how long your hair can get. You cannot extend it with a product, but you can avoid the things that cut it short: crash dieting, low iron, untreated thyroid problems and prolonged stress. Then the real work is keeping what you grew, because most stalled length is breakage at the ends rather than a failure at the follicle.
Watermans is vegan, made in the UK, and has sold over 5 million bottles since 2012.
Watermans products are 100% cosmetic and do not treat medical hair loss. Individual results may vary.
