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Root Touch-Up Calculator

Enter your last color date to see how much regrowth you have today, how often to touch up your roots and your next four dates.

The day your roots were last colored.

in

About 0.5 in a month is the commonly quoted average. Tightly coiled hair often grows a little slower.

How strong is the contrast at your roots?
How much regrowth can you live with?
Which service is it?

How to use the Root Touch-Up Calculator

  1. Enter the date of your last color

    Pick the day your roots were last colored, and keep or change the growth rate. Half an inch a month is the commonly quoted average.

  2. Describe the contrast at your roots

    Gray against dark hair shows almost at once, dark roots against lighter lengths show a clear line, and a subtle color hides regrowth longest.

  3. Choose how much regrowth you can live with

    Pick a quarter, half, three quarters or one inch, then choose the service: permanent color, gray coverage, or highlights and balayage.

  4. Press “Plan my touch-ups”

    You see your regrowth today, the weeks between touch-ups, the next four dates and how many touch-ups that is in a year.

  5. Add the dates to your calendar

    Use “Add dates to calendar” to download the four dates as all-day reminders.

How to use the Root Touch-Up Calculator (52 s)

How the calculator works out how often to touch up roots

Roots are just new hair, so regrowth is growth rate multiplied by time. The calculator measures the days since your last color, converts your monthly growth rate into growth per day, and tells you how much uncolored hair you have now. Then it turns the question around: how many weeks does it take to grow the amount of regrowth you are willing to live with? That is your touch-up interval. 

regrowth today      = growth per month × days since color ÷ 30.44
weeks between       = tolerated regrowth ÷ growth per month × 4.35
touch-ups per year  = 52.14 ÷ weeks between

The growth rate

The default is 0.5 inches a month, the commonly quoted average. It is an estimate, and real rates vary a lot from person to person. A study of Afro-textured hair measured about 256 micrometers a day, which works out to roughly 0.31 inches a month — so if your hair is tightly coiled, a lower rate may be closer to the truth and your touch-ups can be further apart. To use your own number, measure it with the hair growth rate calculator.

Contrast and tolerance

How soon roots bother you depends on contrast. As a rule of thumb, gray against dark hair is noticeable at about a quarter inch, dark roots against lightened hair at about half an inch, and a color close to your natural shade not until three quarters of an inch. The result shows the week your roots become noticeable, and adds a note when that happens before your touch-up.

The dates

The interval is rounded to whole weeks and kept between 2 and 26 weeks. The next date is your last color plus that interval; the three after it repeat the interval. If the first date has already passed, the plan restarts from today. The result also compares your interval with the range usually quoted for the service you chose and says so when you are well outside it.

What it cannot tell you

The calculator does not know how your hair takes color, how fast your shade fades or what your colorist recommends, and those matter as much as regrowth. Treat the dates as a planning aid. Permanent color is a chemical service: do a skin patch test before every application and follow the manufacturer’s instructions. For relaxer touch-ups, which follow different rules, use the relaxer stretch planner.

Root regrowth chart by week

Weeks after color 0.3 in a month0.4 in a month0.5 in a month0.6 in a month
2 0.14 in (0.4 cm)0.18 in (0.5 cm)0.23 in (0.6 cm)0.28 in (0.7 cm)
4 0.28 in (0.7 cm)0.37 in (0.9 cm)0.46 in (1.2 cm)0.55 in (1.4 cm)
6 0.41 in (1.1 cm)0.55 in (1.4 cm)0.69 in (1.8 cm)0.83 in (2.1 cm)
8 0.55 in (1.4 cm)0.74 in (1.9 cm)0.92 in (2.3 cm)1.10 in (2.8 cm)
10 0.69 in (1.8 cm)0.92 in (2.3 cm)1.15 in (2.9 cm)1.38 in (3.5 cm)
12 0.83 in (2.1 cm)1.10 in (2.8 cm)1.38 in (3.5 cm)1.66 in (4.2 cm)

Weeks between touch-ups by the regrowth you tolerate

Regrowth you tolerate 0.3 in a month0.4 in a month0.5 in a month0.6 in a month
¼ in (0.6 cm) 4 weeks3 weeks2 weeks2 weeks
½ in (1.3 cm) 7 weeks5 weeks4 weeks4 weeks
¾ in (1.9 cm) 11 weeks8 weeks7 weeks5 weeks
1 in (2.5 cm) 14 weeks11 weeks9 weeks7 weeks

Usual salon intervals and when roots show

Service or contrast Rule of thumb
Permanent color every 4–8 weeks
Gray coverage every 4–6 weeks
Highlights or balayage every 8–14 weeks
Gray against dark hair noticeable at about 0.25 in (0.6 cm) — week 2 at 0.5 in a month
Dark roots against lightened hair noticeable at about 0.50 in (1.3 cm) — week 4 at 0.5 in a month
Subtle contrast noticeable at about 0.75 in (1.9 cm) — week 7 at 0.5 in a month

All figures are estimates based on steady growth. Your colorist’s advice comes first.

Frequently asked questions

How often should I touch up my roots?
Most people touch up permanent color every 4 to 8 weeks and gray coverage every 4 to 6 weeks, while highlights and balayage can go 8 to 14 weeks. Your own number depends on how fast your hair grows and how much regrowth you can live with — at half an inch a month, half an inch of regrowth takes about 4 weeks.

How fast do roots grow out?
About half an inch (1.3 cm) a month is the commonly quoted average, which is roughly an eighth of an inch a week. One study of Afro-textured hair measured about 0.31 inches a month. If you know your own rate, enter it; if not, measure it with the hair growth rate calculator.

Why do gray roots show so quickly?
Because of contrast, not faster growth. A quarter inch of white or gray against dark hair is easy to see along the part and hairline, while the same regrowth in a shade close to your natural color is hardly visible. That is why the calculator asks about contrast.

Can I touch up my roots every two weeks?
It is not a good habit with permanent color. Each application is a chemical process, and overlapping onto hair that is already colored adds damage. A temporary root spray, powder or tinted concealer covers regrowth between proper touch-ups without any chemistry.

Should I color only the roots or all of my hair?
For a touch-up, only the regrowth. The lengths already hold color, and running permanent color through them every time makes the ends darker, duller and more fragile. If the lengths have faded, a colorist can refresh them with a gentler deposit-only gloss.

Is this the same as a relaxer touch-up?
No. Relaxer touch-ups follow different timing, usually 8 to 12 weeks, and the two services should not be done close together. Use the relaxer stretch planner for those dates.

What if I waited too long between touch-ups?
Nothing is ruined, but a wide band of regrowth is harder to color evenly, so let your colorist know how many weeks it has been. The calculator restarts your plan from today when the planned date has passed.

Sources

Last data update:

  1. Loussouarn G. African hair growth parameters. Br J Dermatol. 2001;145(2):294-297. Afro-textured hair grew about 256 µm/day in the study sample — slower than Asian and Caucasian samples.
  2. U.S. Food and Drug Administration. Hair Dyes. Coal-tar hair dyes must carry a caution statement and directions for a skin patch test before each use.

How we research and update pages: editorial policy. Spotted an error? Tell us.

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