How Fast Does Hair Grow, and Why It Varies

How fast does hair grow? For most men, about a centimetre a month on the scalp. That works out to roughly a third of a millimetre a day, or half an inch a month if you think in inches. The rate barely changes from week to week or from one side of your head to the other. What changes is how much of your haircut that centimetre adds up to, and that is why some men swear their hair grows in days while others go two months without noticing.

Why short hair seems to grow so fast

Your hair is not growing faster than your mate's because your fade is a mess by Friday. It is growing at the same third of a millimetre a day, on a much shorter starting length.

Here is what a week does to each length we cut, worked out from that 1cm a month:

What you had cut	Starting length	After one week	Doubled in
Skin (foil or razor)	0mm	about 2mm of stubble	stubble shows in 3 to 4 days
Grade half	1.5mm	about 4mm	4 to 5 days
Grade one	3mm	about 5mm	about 9 days
Grade two	6mm	about 8mm	about 18 days
Grade three	9.5mm	about 12mm	about 4 weeks
Grade four	13mm	about 15mm	5 to 6 weeks
Scissor cut, 5cm on top	50mm	about 52mm	about 5 months

Read down the last column and the whole question answers itself. A grade one has nearly doubled inside nine days. Five centimetres on top barely moves in a month. So the man who asks us why his hair grows so fast is nearly always the man with the shortest sides in the shop.

Fades show it worst. The bottom of a skin fade starts at nothing, so the bare skin that made the cut has gone within days and the blend starts creeping up your head. We have written up how long a skin fade actually lasts day by day, and the short version is about ten days of looking sharp.

The real reasons yours runs fast or slow

Some men do grow faster than others. It is a smaller difference than the table above, but it is real.

Genes, mostly. How quickly your follicles push hair out is largely inherited. If your dad needed the barber every three weeks, you probably will too.

Hair type. Published measurements of large groups of volunteers have found that tightly curled Afro hair grows more slowly on average than straight hair. It also looks slower than it is, because a coil that grows a centimetre gains much less than a centimetre of visible length. That is part of why a fade on curly hair ages more gently.

Age. Growth tends to slow down as men get older, and the hair often comes through finer.

Your health. Illness, a crash diet, a big shock or certain medicines can slow growth or bring on shedding a couple of months later. If your hair has changed suddenly, or it is coming out in handfuls, that is one for a GP or a dermatologist rather than a barber.

One thing that is not a speed problem is hair that will not get past a certain length. Every hair grows for a few years, then rests and falls out. If your growing phase is on the short side, your hair simply stops at a length, however patient you are. Growing it for longer will not change that, and no trim will either.

Can you make it grow faster?

No, not in any way we can honestly sell you. Trimming the ends does nothing at the root, so regular cuts do not speed anything up. They do stop split ends breaking off, which is why hair that is trimmed now and then often ends up longer than hair that is never cut. Wearing a hat makes no difference either way.

If you are growing your hair out and the wait is the problem, the answer is the haircut, not the growth rate. Keep the sides and neckline tidy and leave the top alone, and the in-between months look deliberate. Our buzz cut grow-out plan goes month by month, with what to book at each point.

Work out your own interval before you book

You do not need a ruler to know your own rate. You need a date. Next time you are in the chair, ask what guard went on the sides and note the day. Most men never do. Then note the morning you look in the mirror and think the cut has gone. The days between those two dates are your interval, measured on your own head rather than taken from a blog. If it comes out shorter than the table suggests, you are one of the quick growers. If it is longer, count yourself lucky.

That number also tells you what to ask for. A skin fade or a grade one that you want kept sharp means coming back every two weeks, and at £17 a time for a skin fade that is worth knowing before you choose the cut. If a fortnight is not going to happen, go a grade longer on the sides. On the table above, one grade buys you a week or more before the cut looks grown out. We have set out the booking interval for each style, from skin fades to longer scissor cuts.

Tell us the date of your last cut when you book a chair. One look at your sides and we can tell which grade went on last time, and we will cut it to last until you are next back in.