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Omnikalc

How long will it take to grow your hair out?

Estimate how many months it will take your hair to grow from its current length to a goal length, at your growth rate and with regular trims.

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Growth rate
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Results

Months to reach your goal

24.9

An average: growth varies with age, genetics, health and the season
In years
2.1
Net growth per month after trims
0.402
Net growth per year
4.82

How fast does hair grow?

Each hair grows from a follicle in the skin through a cycle of three phases:

  • anagen, the growth phase, which lasts about 2 to 7 years on the scalp;
  • catagen, a short transition of a few weeks;
  • telogen, a resting phase of about 3 months, after which the hair falls out and a new one starts.

During anagen, scalp hair grows about 0.5 inch (1.25 cm) a month on average, or about 6 inches (15 cm) a year. Some people grow closer to 0.4 inch, others to 0.6 inch. Losing 50 to 100 hairs a day is normal.

How the calculator works

You enter your current length, your goal length, your growth rate, and how often and how much you trim. The calculator computes:

  1. the length to gain: goal minus current length;
  2. the net growth per month: growth rate minus the average trim per month (length cut × 4.35 weeks ÷ weeks between trims);
  3. the months needed: length to gain ÷ net growth.

If your trims remove as much as you grow, the net growth is zero or negative and you will never reach the goal: space trims out or cut less.

Example

To grow from 4 to 14 inches at 0.5 inch a month with a quarter-inch trim every 12 weeks, net growth is about 0.4 inch a month. The 10 inches take about 25 months, a little over 2 years. Without trims, it would take 20 months.

Typical lengths

Goal Approximate length from the crown
chin 10 to 12 inches
shoulders 14 to 16 inches
armpits / bra strap 18 to 22 inches
mid-back 22 to 26 inches
waist 28 to 32 inches

Keeping the length you grow

  • Trim split ends before they travel up the shaft.
  • Avoid repeated bleaching, high heat and tight hairstyles, which cause breakage.
  • Detangle gently, from the ends upward.
  • Eat enough protein, iron and calories: strict diets often cause shedding a few months later.

Limits

Your terminal length is set mostly by the length of your anagen phase, which is genetic. Sudden hair loss, patches of baldness or very slow growth can come from thyroid problems, iron deficiency, stress, illness or medications and are worth checking with a doctor.

Frequently asked questions

How fast does hair grow?

Scalp hair grows about half an inch, or 1.25 cm, a month on average, roughly 6 inches a year. The rate ranges from about 0.4 to 0.6 inch a month and tends to slow with age.

Is there a maximum length my hair can reach?

Yes. Each hair grows for a growth phase, called anagen, that lasts about 2 to 7 years, then rests and falls out. The length of that phase, which is mostly genetic, sets your terminal length, from shoulder length for some people to waist length or more for others.

Do trims make hair grow faster?

No. Growth happens at the root, so cutting the ends does not change the rate. Trims remove split ends that would otherwise break higher, which helps you keep length, but frequent or large cuts slow your progress, as this calculator shows.

Can supplements speed up hair growth?

Biotin, iron, zinc and vitamin D help only if you are deficient. Sudden hair loss or very slow growth can come from thyroid disease, iron deficiency, stress or medication, and is worth discussing with a doctor or dermatologist.

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Results are estimates provided for information purposes. They do not replace professional advice.

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