How fast does hair grow?

Average hair growth is approximately 1.25cm (0.5 inches) per month, or about 15cm (6 inches) per year. This varies by individual — some grow as slowly as 0.8cm/month while others grow up to 1.7cm/month. Factors include genetics, age, diet, overall health, season and hormones.

Do regular trims help hair grow faster?

Trims do not make hair grow faster — growth happens at the root, not the ends. However, regular trims remove split ends that would otherwise travel up the hair shaft, causing breakage. Without trims, hair may break off at the same rate it grows, resulting in no visible length gain. Trims maintain the quality of growth.

How much should be trimmed when growing hair?

When growing hair, trim just 0.5-1cm every 8-12 weeks. This removes split ends while preserving as much length as possible. If hair is in good condition and not splitting, you can stretch to every 12 weeks. If ends are splitting or damaged, trim 1-2cm every 6-8 weeks to prevent the damage travelling upward.

What affects hair growth rate?

Genetics is the biggest factor. Nutrition (protein, iron, zinc, biotin) supports growth. Stress and illness can slow or pause growth (telogen effluvium). Age slows growth gradually. Scalp health and blood circulation affect the follicle. Hormonal changes (pregnancy, menopause) can affect growth rate and thickness.

CutCalcs

Growth Rate Calculator — Hair Length Predictions

Calculate hair growth over time and predict length at future appointments.

Current Length

Target Length

Growth Rate

Average: 1.25cm/month

Trim Every

Trim Amount

Amount cut each trim

How We Calculate This

This calculator projects how long it will take to grow from current length to target length, accounting for regular trims that slow net growth.

The formula

Net growth/month = Growth rate - (Trim amount / Trim interval in months)

Months to target = Length difference / Net growth per month

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Last updated: February 2026

All calculations are estimates. Always perform a strand test before chemical services.