Many happy customers note longer, stronger, thicker looking hair in as little as 30 days. But we know first hand that month two is when the big results kick in, which is why we created the 60 Day Hair Vitamin Challenge. Everyone is different and will experience different results. Not only do rates of hair growth vary from person to person, an individual's hair can grow at different rates on different areas of the head. Average hair grows at a rate of 0.5 inches (1.25 cm) per month.