The average is published, yours is measurable

What the published figure actually is

The clinical reference figure for scalp hair is about a third of a millimetre a day, which the same reference converts to roughly a centimetre a month and about fifteen centimetres over a year. In inches that monthly figure is a little under half an inch, which is where the half an inch a month repeated everywhere comes from, usually rounded up on the way.

The other half of that reference matters more for a grow-out than the rate does. A follicle spends years in its growing phase before it rests and sheds, which is why scalp hair reaches lengths that body hair never does. A grow-out is therefore not a race against the follicle. It is a wait, and the wait is bounded by how long you are willing to look like something in between.

So treat the monthly figure as what it is: an average across people rather than a promise to you. It is the right tool for a rough plan and the wrong tool for deciding whether to keep going in week six.

Why the average does not answer your question

Two heads given the same number of months arrive in different places, and not only because the rate differs between people. Where new length shows up first is decided by growth direction, by how dense the hair is, and by where the previous cut left its hardest edges.

Density decides whether new growth reads as a style or as a gap. On dense hair a little new length stands up and holds a shape. On finer hair the same growth lies down, so the head looks unchanged for weeks and then seems to change all at once.

The previous cut decides the rest. A blunt front edge and a high skin fade both leave a line that has to grow out rather than blend out, and a line stays visible far longer than the length it represents. That is why somebody growing out a fade feels no progress for a month while somebody growing out a scissor cut sees progress immediately.

Measure your own rate, between two haircuts

The rate you can act on is yours, and getting it costs nothing beyond paying attention twice.

• Pick a landmark that does not move: the top of an ear, the bottom of the hairline at the back, a parting you always wear. A general impression of your whole head is useless here, because the crown and the nape do not behave the same way.
• Photograph it on the day of a haircut, from the same distance, in the same light, hair dry and unstyled. A phone at arm length against a plain wall is enough, as long as it is the same wall every time.
• Photograph it again on the day of the next haircut and note how many weeks apart the two were. That difference, spread across those weeks, is your rate rather than a population figure.
• Write the number down somewhere you will find it again. This is the kind of thing everybody re-measures because nobody records it, and one measurement serves every grow-out you will ever plan.

The stage nobody warns you about

Every grow-out has a middle. The sides have outgrown the fade but are not long enough to sit flat, the top moves but is too short to fall anywhere on purpose, and the whole thing reads as untidy rather than as a longer haircut. It tends to arrive at about the point you were expecting to start seeing a result.

This is not a sign that something has gone wrong. It is the only route from a short cut to a long one, and the people whose grow-out worked are the ones who were expecting it. The ones who were not expecting it book a cut, which takes them back to the start while feeling like progress.

What gets you through it is a trim that does not touch the part you are growing. Sides and the neckline can be tidied as often as you like while the top is left alone, which keeps the haircut looking deliberate while the length you care about accumulates. The guide here on how often to get a haircut covers that rhythm.

Which targets are a long wait, and which are not

Sorting the usual targets by how much waiting they really involve is more useful than any single figure, because the length is only part of what you are waiting for.

• A buzz to a crop is the shortest honest jump, because a crop wants a little length on top and almost nothing anywhere else. It is the grow-out most likely to be finished rather than abandoned.
• A fade to one uniform length takes longer than the length involved suggests, since you are waiting for the shortest part of a gradient to catch up with the longest part of it.
• A short cut to a length that ties back is the long one. Plan it in seasons rather than weeks, and expect the middle stage to last a while, because it has more ground to cover.
• A blunt fringe back to a side parting is its own case. The length arrives quickly and the hard front edge takes much longer to stop being the first thing anybody notices.

See the target before you wait for it

The expensive mistake here is not waiting too long. It is waiting months for a cut that was never going to suit the face it was growing on, which is a thing you find out at the end, once the length has been paid for in full.

That is what Lineup is for. Render the cut you are growing towards on your own selfie, look at it against your own hairline and your own density rather than on the model in the reference photo, and then decide whether the wait is worth starting. It is a cheaper way to find out than a season of growing something you then cut off.

If the answer is yes, keep the render. It is a useful thing to have during the middle stage, on a day when the mirror is not showing you anything encouraging.

See these on your own face

• buzz cut
• french crop
• man bun

Questions