Hair Length Tracker: Record Your Hair Measurements

Type your hair length measurements with their dates to see how much your hair has grown, your average growth per month and an estimated date for your goal length.

The hair length tracker turns a list of dated measurements into a clear record of progress: the change between each measurement, your average growth per month and, if you set a goal, the date you might reach it.

What this tool does

You keep one list, with one measurement on each line. The tracker sorts it by date, works out the change and the rate for each step, and shows the overall figures above a table. Your list is saved in your own browser, so it is still there on your next visit. It is not stored on the website.

What you enter

Field	What to enter	Limits
Your measurements	One on each line: the date as year-month-day, a space, and the length. Example: 2026-03-01 42.5	Up to 60 lines. No future dates. One measurement for each date.
Unit of all lengths	Centimeters or inches	1 to 250 cm, or 0.5 to 100 in
Goal length	The length you are aiming for, in the same unit	Optional

Use a point for decimals. A comma, semicolon or colon between the date and the length is also accepted.

How the result is worked out

Change = last length − first length. Days = the number of days between those two dates.
Average per month = change ÷ days × 30.44, because an average month has 30.44 days.
Each row of the table shows the same figures for one step: the change since the measurement before it, the days between them and the rate per month.
With a goal, days needed = (goal − last length) ÷ your average daily rate, rounded up. The estimated date is your last measurement date plus those days.

Messages you may see

"Enter your measurements." when the list is empty.
"Line 2 is not valid. Write a date and a length, for example 2026-03-01 42.5." for a line in another format.
"Line 3: 2027-01-01 is in the future." for a date after today.
"Line 4: the length must be between 1 and 250 cm." for a length outside the limits.
"Line 5: there is already a measurement for 2026-03-01." for a repeated date.

When several lines have a problem, the first is described and the others are counted, for example "2 more lines have a problem."

How to use it

Measure the same section of hair each time, pulled gently straight, from the same starting point, such as the hairline at the forehead or the nape.
Add a new line with the date and the length about once a month.
Select "Show my progress".
Use "Clear the saved list" to remove the list from this browser.

Worked example

Three lines: 2026-01-05 40, 2026-03-05 42.4 and 2026-06-01 45.5, in centimeters, with a goal of 50.

The result is +5.5 cm in 147 days, an average of 1.14 cm a month. The steps were +2.4 cm in 59 days (1.24 cm a month) and +3.1 cm in 88 days (1.07 cm a month). At the average rate, 50 cm is about 121 days away, around 30 September 2026.

Limits and assumptions

Scalp hair grows about 1 to 1.5 cm, or about half an inch, a month on average, and the rate differs from person to person. The goal date assumes no trims and no breakage. A shorter measurement usually means a trim, breakage at the ends or a difference in how you measured. The tracker warns you when a rate is faster than hair normally grows, which usually means a typing or unit mistake. It measures length only: for thinning or shedding, see How to Track Hair Loss Before a Dermatologist Visit and a doctor or dermatologist.

Related on ArniSun

Frequently asked questions

How often should I measure my hair?

About once a month. Hair grows slowly, so smaller gaps mostly show differences in how you held the tape.

Where is my list saved?

In the storage of the browser you are using, on your own device. It does not appear on another device, and it is lost if you clear the browser's data. Keep a copy if the record matters to you.

Why is my hair not getting longer, although it grows?

The ends may be breaking as fast as the roots grow. Gentle detangling, less heat and regular small trims help hair to keep its length. See [[BLOG-066]].