How Long Growing Out Grey Actually Takes
Deciding to stop colouring is a decision about time more than about hair. The arithmetic is a single division — the length of coloured hair you are carrying, divided by how fast it grows — and knowing the answer in advance is most of what makes the process bearable.
The number, by length
From the going-grey timeline calculator, at the default growth rate:
| Coloured length | To full grow-out | In years | To halfway |
|---|---|---|---|
| 10 cm | 8 months | 0.7 years | 4 months |
| 20 cm | 16 months | 1.3 years | 8 months |
| 30 cm | 24 months | 2 years | 12 months |
| 45 cm | 36 months | 3 years | 18 months |
| 60 cm | 48 months | 4 years | 24 months |
At 30 cm of coloured hair — roughly shoulder length — the full grow-out is 24 months. That is the honest headline, and it is why so many grow-outs are abandoned in month five: the halfway point arrives at 12 months, and month five is nowhere near it.
The milestones on a shoulder-length grow-out
| Grown out | Months in | Root length |
|---|---|---|
| 25% | 6 months | 7.5 cm of root |
| 50% | 12 months | 15 cm of root |
| 75% | 18 months | 22.5 cm of root |
| 100% | 24 months | 30 cm of root |
Reading the table as a series of stages rather than one long wait is the practical difference between finishing and giving up. Each row is a point at which the hair looks measurably different from the row before.
Why growth rate is the variable you cannot change much
Scalp hair grows at a fairly consistent rate across most people, and while it varies a little with age, health and genetics, it is not something a product moves meaningfully. Anything promising faster grow-out is selling you the denominator of a division it cannot affect.
What you can change is the numerator. Cutting length is the only lever that genuinely shortens the timeline, which is why almost every successful grow-out involves going shorter than the person originally intended.
What actually shortens it
Cut length off. Going from 45 cm to 20 cm takes the wait from 36 months to 16 — a saving of 20 months for one decision.
Cut gradually. Trimming every few months removes coloured ends continuously and shortens the tail of the process without a single dramatic change.
Go shorter than feels necessary once. A single decisive cut is the fastest route and the one people resist longest.
Living with the line
The demarcation line between grey root and coloured length is the visible part of the process, and it is sharpest in the middle months when the root is long enough to see and short enough to look deliberate.
Blending with highlights or lowlights softens the line without restarting the clock, because it does not put permanent colour back on the root.
Gloss or toner can bring the coloured length closer in tone to the incoming grey, which narrows the contrast rather than hiding it.
Style does a surprising amount — a parting moved, or texture through the root, and the line stops reading as a line.
What restarts the clock is permanent colour on the root. Anything that deposits on new growth puts you back at month zero for that length, which is worth knowing before a salon visit in month seven.
Measuring your own number
Measure from the scalp to the end of the coloured hair — not total length, since any grey you have already grown does not count. Put that figure into the calculator with your own growth rate if you know it, and read the milestone table rather than the total.
Then decide the cut. That is the only real decision in the whole process: the timeline follows from it mechanically, and no amount of product changes the division.
If you change your mind
Going back is not a failure and it is quicker than going forward — covering grey is a single appointment where growing it out is a year. The coverage calculator handles that side, and the honest thing to know is that the two options are not symmetrical in effort, which is worth weighing before starting rather than in month six.
What the timeline assumes
A steady growth rate. The default is an average; individual rates vary and slow somewhat with age. If you know yours, use it — the whole answer is proportional to it.
No further colour on the root. Obvious, and the assumption most often broken.
Even growth. Hair does not all grow in step, so the line is a band rather than a sharp edge, which in practice helps rather than hinders.
That length is the only thing being removed. If you are also changing style, the cut may shorten the timeline for free.
The months people find hardest
Consistently the ones around a third to halfway — roughly months 0 to 12 on a 30 cm grow-out. The root is too long to ignore and too short to be the dominant colour, and the end is not yet in sight.
Knowing in advance that this band exists, and roughly when it falls, is the single most useful thing the calculator provides. It converts "this looks terrible and will never end" into "this is month eight of fifteen, which is the part everyone says is worst".
A plan worth following
Measure and calculate first, so the number is a fact rather than a fear.
Decide the cut up front — it is the only lever, and deciding it once is easier than deciding it repeatedly.
Book trims at intervals rather than waiting to feel bad about the ends.
Plan a blending step for the middle months, before you need it.
Photograph the root monthly. Progress is invisible day to day and obvious across photographs, and that is the difference between finishing and not.
None of this is a recommendation either way. Colouring and not colouring are both entirely reasonable, and the only thing worth insisting on is that the choice is made with the timeline known rather than discovered halfway through it.