Growing it out
Hair growth timeline calculator
Scalp hair grows about 1 cm (roughly ½ inch) a month. Enter your length now and a goal, or a date, and see when you get there, trims and all, with a faster-to-slower range.
How to use it
- Your hair now. Measure from a fixed point, such as the nape hairline, to the ends with the hair straight, and choose centimetres or inches.
- Goal or date. Enter a goal length (or pick a named one) to get a date, or choose a date to see how long your hair should be by then.
- Rate. Typical uses 1 cm a month and shows faster (1.25 cm) and slower (0.85 cm) growth as a range. If you know your own rate, enter it; if you colour your hair, your roots tell you: 1.5 cm of regrowth six weeks after colouring is about 1.1 cm a month.
- Trims. Each trim takes length off at the end of every interval. Trimming 1 cm every 12 weeks costs about a third of a centimetre a month.
Worked example
Hair 30 cm from the nape, aiming for 45 cm (just past waist length on a woman of average height), with 1 cm trimmed every 12 weeks: you get there in about 22 months. Skip the trims and it takes about 15 months.
The chart dips at each trim. Growth is never perfectly steady, so treat the date as a guide and re-measure every few months.
Why the range?
Scalp hair grows about 1 cm a month on average, but people differ. In the measurements summarised in a 2020 review, average growth was about 280 micrometres a day for African hair, 367 for Caucasian hair and 411 for Asian hair: roughly 0.85, 1.1 and 1.25 cm a month. Within any group, individuals vary further.
Each hair also grows only during its growth phase (anagen), which lasts about two to seven years before the hair rests and sheds. That sets a natural maximum length that differs from person to person, which is why some people can grow hair to the hips and others stop near the shoulders.
Breakage takes length off the ends just as trims do. Gentle brushing and less heat will not speed the roots up, but they help you keep the length that grows.
Sources
- Cleveland Clinic, Hair follicle: hair grows about 1 centimetre a month; the growth phase lasts two to seven years, followed by a short transition and a resting phase of up to four months.
- Leerunyakul K, Suchonwanit P. Asian hair: a review of structures, properties, and distinctive disorders. Clinical, Cosmetic and Investigational Dermatology 2020;13:309–318, Table 1: growth of 411 ± 53 µm a day (Asian), 367 ± 56 (Caucasian) and 280 ± 50 (African).
Monthly rates here use an average month of 30.44 days. The named lengths come from the hair length chart, which explains how they were estimated.
Questions
How fast does hair grow in a month?
About 1 cm on average, a little under half an inch, which adds up to around 12 cm (almost 5 inches) a year. Published averages for different groups run from about 0.85 to 1.25 cm a month, and individuals vary more than that.
Do regular trims make hair grow faster?
No. Hair grows from the follicle in the scalp, and cutting the ends does not change that. Trims remove split and damaged ends, which can help you keep the length you grow, but each one also takes some off, which is why this calculator subtracts them.
Why does the calculator say I will never reach my goal?
Because the trims you entered take off as much hair as grows between them, or more. At 1 cm a month, trimming 3 cm every 12 weeks leaves no net gain. Trim less often or take less off, and the date appears.
How do I measure my hair length?
Use a soft tape measure. Hold one end at the hairline at the nape of your neck and run it straight down to the ends of a straightened section at the back. Curly hair can be much longer stretched than it looks, so measure it gently stretched and always the same way.
Is there a limit to how long my hair can grow?
Yes, for each person. A hair grows only during its growth phase, which lasts roughly two to seven years, then rests and falls out. Someone with a short growth phase reaches a shorter maximum length however patient they are.