Hair Growth Calculator
Calculate exactly how long it will take to grow your hair from its current length to your target. Factor in hair type, age, and health for a personalized growth timeline.
Your Hair Growth Timeline
Month-by-Month Timeline
Tips to Maximize Growth
How Fast Does Hair Grow
Human hair grows at an average rate of about 0.5 inches (1.25 cm) per month, or roughly 6 inches (15 cm) per year. However, this varies significantly based on genetics, ethnicity, age, health, and hair care practices. Asian hair tends to grow the fastest at up to 6.3 inches per year, while African-textured hair grows closer to 4 inches per year. The anagen (active growth) phase lasts 2-7 years, which determines your maximum possible hair length.
Factors That Affect Hair Growth Speed
Genetics and ethnicity: The single biggest factor. Your genes determine your growth rate, anagen phase length, and maximum hair length. Asian hair has the longest growth phase on average.
Age: Hair grows fastest between ages 15-30. After 30, growth gradually slows. After 50, it can slow to 0.25 inches per month or less due to reduced follicle activity.
Nutrition: Hair is made of keratin protein. Adequate protein intake, along with iron, zinc, biotin (B7), and vitamins A, C, D, and E are essential. Deficiencies directly slow growth.
Health and stress: Chronic stress triggers telogen effluvium (excessive shedding). Thyroid disorders, hormonal imbalances, and autoimmune conditions also impact growth. Good sleep and exercise promote healthy circulation to the scalp.
How to Speed Up Hair Growth
While you cannot exceed your genetic growth rate, you can ensure you are reaching your full potential. Eat a protein-rich diet with adequate iron and biotin. Consider a daily multivitamin or biotin supplement (2500-5000 mcg). Massage your scalp for 5 minutes daily to increase blood flow. Minimize heat styling, chemical treatments, and tight hairstyles that cause breakage. Use a silk or satin pillowcase to reduce friction. Trim split ends every 8-12 weeks — this does not speed growth but prevents breakage that makes hair appear to grow slower.
Hair Growth Calculator Accuracy
This calculator uses published scientific data on average hair growth rates by ethnicity, age group, and health factors. It provides an estimate based on population averages — your individual rate may be faster or slower. For the most accurate results, measure your hair growth over 2-3 months and compare to our estimates. If your hair seems to grow much slower than expected, consult a dermatologist to rule out underlying conditions.