Hair & care · Always free
Hair Growth Calculator
Plan the grow-out from your current length to a target. Adjust the monthly growth assumption and the length you expect to trim, then see an estimated timeline and progress milestones. This is a planning calculator, not a prediction of your individual biology.
A clearer next step
Less guessing.
More useful ideas.
Answer the questions to get an explained result you can save. No photo, account or payment is required.
- See what your answers mean
- Compare practical next steps
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How to use the hair growth calculator
- 1Choose inches or centimeters and enter current and target length using the same measuring point.
- 2Use the example monthly rate or replace it with your own observed average. Add the average length removed in trims per month.
- 3Review the estimated time and milestones. Recalculate when your observations or trimming plans change.
Method & limitations
Net monthly length gain = growth rate minus average monthly trim allowance. Months to target = (target length − current length) ÷ net gain, with zero months if the goal is already reached. If net gain is zero or negative, we show that the target cannot be reached under those assumptions. The example rate is 0.5 inches (1.27 cm) per month. It is editable and is not a personal forecast.
Method documented by HairSelector · Reviewed · No clinical or professional accuracy validation claimed.
A worked grow-out example
Going from 6 inches to 12 inches requires 6 inches of retained length. At an assumed half inch per month with no trims, the model gives 12 months. If you allow for an average trim of 0.1 inch per month, retained length is 0.4 inch per month and the same target takes 15 months. The arithmetic explains the estimate; actual growth and breakage may differ.
Measure retained length consistently
Choose one section and one starting point, then use the same technique each time. For textured hair, comparing stretched length one month with unstretched length the next can make the change misleading. Track the measuring method alongside the number. The calculator does not infer a rate from your gender, age or ethnicity.
Use trims as an average allowance
If you plan to remove half an inch every five months, enter 0.1 inch as the monthly trim allowance. This smooths occasional trims into a planning model; it does not schedule haircut dates. Milestones show the projected length under the same assumptions. Unexpected shedding or a scalp concern is outside the purpose of this cosmetic planning tool.
Common questions
How fast does hair grow per month?
The example setting is about 0.5 inches, or 1.27 cm, per month, as described in the AOCD patient reference below. Individual rates vary. Replace it with a measured average if you have one.
Does trimming make the calculator predict faster growth?
No. Trimming removes length in this model. The calculator subtracts the average trim allowance from the assumed growth rate rather than claiming that a haircut changes follicle growth.
Can I switch between inches and centimeters?
Yes. Switching units converts the entered lengths and rates using 1 inch = 2.54 cm. The estimated timeline remains the same apart from display rounding.
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