Beauty Calculators
Hair growth goal.
Enter where your hair is now, where you want it and how fast it grows. Add the trims you plan, which subtract from growth, to see the months and the calendar date you reach the goal, plus a table of expected length every three months. Runs in your browser.
Length and rate
Time to goal
Fill the form and press Calculate.
Worked example
Your hair is 15 cm and you want 30 cm. At 1.25 cm a month and no trims: (30 - 15) / 1.25 = 12 months. Trim 1 cm every 3 months and the net gain becomes 1.25 - 1 / 3 = 0.917 cm a month, so it takes 15 / 0.917 = 16.4 months. The table shows 18.75 cm after 3 months at the 1.25 cm pace.
How it works
months = (goal - current) / net growth per month, where net growth = growth per month - trim size / months between trims. If trims remove as much as grows back, the goal is never reached and the tool says so. The date adds those months to your start date using an average month of 30.44 days. The table shows current length plus net growth times 3, 6, 9 months and so on.
The growth rate is yours. The page starts at about half an inch (1.25 cm) a month, the commonly quoted average also given by the American Academy of Dermatology. Rates differ between people and over time, so treat the result as a plan, not a prediction. It also measures from the roots, so wavy or curly hair, which looks shorter than its true length, needs a goal in stretched length if that is how you measure.
This is a planning tool. Sudden or unusual hair shedding is a question for a healthcare professional, not a calculator.
Sources and basis (checked 2026-10-04): American Academy of Dermatology, What kids should know about how hair grows (about half an inch a month); the rest is arithmetic on your inputs.
FAQ
How long does it take to grow hair to a certain length?
Divide the length you need to gain by your monthly growth. At 1.25 cm (half an inch) a month, 15 cm takes 12 months. Use your own measured rate if you have one.
How fast does hair grow per month?
The commonly quoted average is about half an inch (about 1.25 cm) a month, about 6 inches a year, according to the American Academy of Dermatology. Individual rates vary.
Do trims make hair grow slower?
Trims do not change how fast it grows from the scalp, but they remove length, so your visible length gains less. The calculator subtracts trim size over the months between trims.
How do I measure my own growth rate?
Measure from the same point, for example the nape to the end of a section, on the same day each month for two or three months, and take the average gain.
Can this predict hair loss or regrowth?
No. It is arithmetic on a rate you enter. If you are concerned about shedding or thinning, speak to a healthcare professional.
Disclaimer
Not medical advice. This projects length from a growth rate you enter and is not a diagnosis or a prediction of regrowth. Speak to a healthcare professional about hair loss or scalp conditions.