How this calculator works
Hair grows at an average rate of about half an inch (roughly 1.25 cm) per month for most people, though genetics, health, hair care, and age can shift that rate. This calculator divides the length you still need to grow by your chosen monthly growth rate.
The formula
Months needed = (Desired length − Current length) ÷ Monthly growth rate. If your desired length is shorter than your current length, no growth time is needed.
This is a general estimate for planning purposes, not a medical or dermatological prediction. Actual hair growth varies by individual and can be affected by health, styling, and hair breakage.
Last reviewed August 2026