Every hair on our head will be somewhere in the hair growth cycle, which has three phases to it. In normal and healthy circumstances, we have 85-90% of our hairs in the growth (anagen) phase. The rest will be in the Transition (Catagen) or Resting (Telogen) phase. During the growth phase our hair will grow on average ½ inch per month, but a lot of factors will influence this. Age, hair type, overall health and other health conditions will all influence hair growth speed. How long each hair remains in the growth phase can differ quite dramatically and therefore the length each hair can grow to differs as well. The growth phase will on average last anywhere between 2-8 years. At the end of this growth phase, the hair is cut off from the blood supply and eventually it will fall out. This happens because a brand-new hair is growing from scratch and pushes the old hair out of the way. All of this is part of a healthy hair growth cycle.
So, what does that mean in terms of the length our hair can grow? At ½ inch per month, a hair left on its own will grow anywhere between 12-48 inches in length. For context 48 inches is 4 foot or 120cm in length. Very few people will ever want to grow their hair that long. What this does mean is that for men and women with long hair, not ever hair will grow down to the length of the rest of the hair. While these hairs never make it down to the weight line for the long hair style you may be going for, they will still become damaged like the rest of the hairs. They will split and fray just like any hair, but when you go to get your hair cut only the split ends that reach the weight line will be cut. It is these hairs that create the hairs that don’t sit in line with the longer healthier hairs.
There are many products on the market that claim to make hair grow faster or to make your hair grow for longer by extending the growth phase. How effective these products can be is debatable as it can be very tricky to prove in clinical trials. There are so many variables that effect hair growth that controlling them completely can be very tricky. Shampoos, leave-in treatments, supplements and low-level laser devices are among the products on the market that can potentially help to grow hair faster and longer. However, they aren’t guaranteed to work for everyone so take some caution if exploring any products that do claim this.