Hair grows about half a millimetre a day. Somewhere between one and one and a half centimetres a month, a little slower in winter, a little faster in your twenties than your fifties. So if you are staring at the same length in the mirror that you saw three months ago, the honest answer is not that your hair stopped growing. It is growing right now. Something else is eating the length before you get to see it.
I'm Lynn Yap, a cosmetic chemist and the founder of CLYNN by Nature. I have been formulating hair care for over twenty years and I mix every one of our formulas myself. Slow growth is one of the questions I get most, and almost every time, the answer is one of six things. Here they are, starting with the ones that are easy to fix.
1. Your hair is breaking, not slow
This is the most common reason by a long way, and the easiest to misread. Hair that breaks at the ends or snaps mid shaft is losing length from the bottom while new hair arrives at the top. On a good day it looks like a standstill. On a bad day, it looks like your hair is getting shorter.
How to tell: look for shorter pieces sticking out at the crown and around the hairline, a rough or split feel along the mid lengths, and lots of small broken hairs in your brush instead of long ones with the root attached. If that sounds familiar, your hair growth is fine. The hair is just not surviving.
What helps: cut back on heat, stop rough towel drying, and be gentler with brushing when your hair is wet. Wet hair stretches and snaps far more easily than dry hair. If you use bleach or peroxide, that is almost certainly part of it.
2. Your last shed is still working its way through
Hair does not fall out the moment something stresses your body. It drops roughly two to three months later. So a bad illness, a difficult birth, a crash diet, surgery, or a stretch of brutal stress in January shows up as thinning in March or April.
That is telogen effluvium, and it resolves on its own once the trigger is gone. What it does to growth is create a gap: for a few months, you lost hair faster than it was being replaced, so your total length looks stuck. It is not. It is catching up. Our article on stress and shedding goes into the timeline in more detail if you want the full picture.
3. Your scalp is not in good enough shape
I have written about this before and I will keep saying it, because it is the part most people skip. Hair grows out of a follicle. The follicle lives in your scalp. If the scalp is inflamed, flaky, itchy, or coated in product buildup, you have created a rough environment for the one thing that actually makes hair.
You do not need a scalp routine with twelve steps. You need a clean, calm scalp and a bit of blood flow. A gentle shampoo used properly and a scalp tonic massaged in with your fingertips does more than any length of supplement shelf. If your scalp itches or flakes and you have not dealt with it, start there. Our guide on scalp health and growth is the place to begin.
4. Genetics, and the honest part about it
Pattern hair loss runs in families, and it changes the hair you grow, not just the amount. Each cycle, the follicle produces a slightly finer, shorter strand. That is why someone with pattern thinning often finds their hair will not grow past a certain point any more. It is not growing slower exactly. It is growing smaller.
No shampoo reverses that on its own. What a good routine can do is keep the scalp healthy enough that the hair you still have stays as strong as it can, and give the follicle the best conditions it is going to get. If you want the mechanism explained properly, our piece on DHT and the scalp is the one to read.
5. The boring stuff that actually shifts the needle
Before anyone buys anything, check these five. They are unglamorous and they matter more than most products.
- Protein. Hair is made of it, and a low-protein diet shows up in hair before it shows up anywhere else.
- Iron and ferritin. Low iron is one of the most common findings in women with poor regrowth, and it is a simple blood test.
- Thyroid. Both an underactive and an overactive thyroid change the hair cycle.
- Crash dieting and very low calorie stretches. Your body deprioritises hair when it thinks food is scarce. That is a feature, not a fault.
- Sleep and stress. Cortisol does not care about your hair goals.
If you are ticking several of these, see your GP and ask for the bloods. No serum beats low ferritin.
6. How you wash and style it
Daily hot water and a harsh detergent strip the scalp and rough up the strand. Silicones and heavy oils coat the hair and can build up on the scalp if you never clarify. Very tight styles pull on the follicle, and over time that is a real cause of thinning at the edges. None of this stops growth, but all of it makes your hair look shorter and thinner than it is.
So what actually speeds it up?
Nothing doubles your growth rate. Anyone promising that is selling something. What you can do is remove the things slowing you down, and support the growth you already have.
A simple version, in order: fix any health cause with your GP, get your scalp clean and calm, stop the breakage, then add a scalp tonic for blood flow and follicle support. Give it a full season. Hair grows about a centimetre a month, so a difference you can see needs three to four months of consistency. Six is better.
If you want a starting point that covers scalp and lengths without guesswork, our anti-hair-loss range is where I would begin. And if you are not sure which of these six is your problem, the honest move is to take our free hair analysis quiz first. It asks about shedding, scalp, breakage, and history, then points you at a routine that fits, instead of you buying a bottle and hoping.
One last thing. If your hair is coming out in patches, or you are losing it fast, or you feel unwell, that is a doctor conversation, not a shampoo one. This article is education, not medical advice.
