Understanding the Hair Growth Cycle

Hair growth may seem simple on the surface, yet every strand on the scalp follows a complex biological rhythm known as the hair growth cycle. Rather than growing continuously, hair develops through a series of repeating phases that determine when it grows, rests, and eventually sheds.

Learning about the hair growth cycle stages provides valuable insight into how hair grows and why hair behaves the way it does. It explains everyday experiences such as natural shedding, differences in hair length, and why hair density can change over time.

Each hair follicle works independently, moving through the cycle on its own schedule. This staggered timing ensures that new hair is constantly growing while older strands complete their lifecycle.

How Hair Grows

Hair begins its life beneath the surface of the skin in a structure called the hair follicle. These tiny pockets sit within the scalp and contain the cells responsible for producing each strand.

Inside the follicle, specialised cells multiply and form the hair shaft. As new cells develop, older cells are pushed upward through the scalp, gradually forming the visible strand of hair.

Hair is made primarily from keratin, a structural protein that gives hair its strength and durability. Once the strand emerges from the scalp, the visible part of the hair is no longer biologically active, though the follicle beneath the skin continues working throughout the growth cycle.

The scalp typically contains between 80,000 and 120,000 hair follicles, each repeating the same pattern of growth and renewal.

The Structure of Hair

Before exploring the hair growth cycle stages, it helps to understand the structure of a hair strand.

Each strand of hair has three main layers.

Cuticle

The cuticle forms the outer protective layer of the hair. It consists of overlapping cells that protect the inner layers and influence the hair’s texture and shine.

Cortex

The cortex makes up the largest part of the hair strand. It contains keratin fibres and pigment cells that determine the hair’s colour and strength.

Medulla

The medulla is the central core of the hair. Not all hair types contain a medulla, but when present it contributes to the overall structure of the strand.

Although the visible strand itself is not alive, the follicle beneath the scalp is highly active during certain stages of the growth cycle.

The Four Hair Growth Cycle Stages

The hair growth cycle stages consist of four phases. These stages determine how hair grows, pauses, and eventually sheds before the cycle begins again.

Each follicle repeats these stages many times throughout life.

Anagen Phase (Growth Stage)

The anagen phase is the active growth stage of the hair cycle. During this phase, cells in the hair root divide rapidly and produce the hair shaft.

As new cells form, the strand continues to lengthen and emerge further from the scalp. Blood vessels surrounding the follicle supply oxygen and nutrients that support this active growth.

The anagen phase can last between two and seven years, depending largely on genetics. The length of this phase determines how long hair can potentially grow.

Key characteristics of the anagen phase include:

• Continuous hair growth
• Rapid cell division in the follicle
• Strong connection between the hair root and blood supply

At any given time, around 85–90 percent of scalp hairs are typically in this stage.

Catagen Phase (Transition Stage)

The catagen phase marks the transition between active growth and the resting period of the hair cycle.

During this stage, the follicle begins to shrink and hair growth gradually slows. The hair strand separates from the blood supply that supported its growth during the anagen phase.

The follicle itself becomes smaller as it prepares to enter the resting stage.

This phase is relatively short, lasting approximately two to three weeks, and affects only a small percentage of hairs on the scalp at any one time.

Telogen Phase (Resting Stage)

The telogen phase is the resting period of the hair cycle. During this stage, the hair remains anchored within the follicle but no longer grows.

Although growth has stopped, the strand stays in place while the follicle prepares for the next phase of the cycle.

Typically, around 10–15 percent of scalp hairs are in the telogen phase at any given moment.

This stage generally lasts three to four months before the hair moves into the shedding phase.

Exogen Phase (Shedding Stage)

The exogen phase is the final stage of the hair cycle, during which the hair strand is released from the scalp.

Shedding during this phase is completely natural and allows new hair to begin growing from the same follicle.

Most people lose between 50 and 100 hairs per day, particularly during brushing, washing, or styling. These hairs are usually those that have already completed the earlier stages of the cycle.

Once the hair sheds, the follicle returns to the anagen stage and begins producing a new strand.

How Fast Hair Grows

When people ask about how hair grows, they are often curious about the speed of hair growth.

On average, scalp hair grows around one centimetre per month, though this rate can vary between individuals.

Over the course of a year, hair may grow approximately 12 to 15 centimetres, depending on genetics and other biological factors.

Hair growth rates can also change slightly with age. Younger individuals often experience faster growth, while the cycle may slow gradually over time.

Seasonal variations may also influence growth speed. Some studies suggest hair may grow slightly faster during warmer months compared with colder seasons.

Factors That Influence the Hair Growth Cycle

Several factors can influence the timing and behaviour of the hair growth cycle stages.

Genetics

Genetics play a major role in determining how long the anagen phase lasts. Individuals with longer growth phases often find that their hair grows longer before reaching the shedding stage.

Age

Hair cycles can change gradually with age. Over time, the growth phase may shorten slightly, which can influence hair density and length.

Hormonal Changes

Hormones can affect the timing of the hair cycle. Changes related to life stages may influence how follicles move through the growth and resting phases.

Nutrition

Hair follicles require nutrients to support the production of new cells during the growth stage. Balanced nutrition contributes to the overall environment in which follicles function.

Hair Care Habits

Regular scalp care and gentle handling of hair can help maintain the condition of both the hair strands and the follicles beneath the scalp.

The Role of the Scalp in Hair Growth

Hair growth begins beneath the surface of the skin, which means the condition of the scalp plays an important role in supporting the hair growth cycle.

The scalp contains thousands of follicles, oil glands, and blood vessels that contribute to the environment where hair develops.

Maintaining a balanced scalp environment helps ensure follicles can continue repeating the natural cycle of growth, rest, and renewal.

Factors that influence scalp health include:

• Natural oil production
• Circulation within the scalp
• Cleansing and hair care routines
• Environmental conditions

A well-maintained scalp supports the ongoing activity of the follicles responsible for hair production.

Why Hair Shedding Is Normal

Shedding hair can sometimes be surprising, yet it is an essential part of the hair growth cycle stages.

During the exogen phase, older hairs are released so that new hairs can begin growing from the follicle beneath.

This process allows the scalp to constantly renew itself. Since follicles operate independently, shedding happens gradually rather than all at once.

Daily shedding is therefore a natural sign that the cycle is continuing as expected.

How Many Hair Cycles Occur in a Lifetime

Each hair follicle repeats the hair growth cycle many times over the course of a person’s life.

A single follicle may produce 20 to 30 separate hairs during a lifetime, with each strand completing the same sequence of growth, rest, and shedding.

Over time, the duration of each phase may change slightly. The anagen phase may become shorter with age, which can influence hair length and density.

Even so, the follicle continues repeating the cycle, allowing new strands to grow as older ones reach the end of their lifecycle.

Understanding Your Hair’s Natural Growth Process

Hair growth is not a continuous process but a carefully timed cycle that repeats throughout life. By understanding the hair growth cycle stages, it becomes easier to recognise why hair sheds, how new strands develop, and why growth patterns vary between individuals.

Each follicle follows its own rhythm, ensuring the scalp maintains consistent coverage as older hairs shed and new ones begin to grow.

Learning about how hair grows provides a clearer picture of the natural processes taking place beneath the surface of the scalp.

Frequently Asked Questions

What are the hair growth cycle stages?

The four hair growth cycle stages are anagen (growth), catagen (transition), telogen (resting), and exogen (shedding).

How fast does hair grow?

Scalp hair typically grows around one centimetre per month, though growth rates vary depending on genetics, age, and overall health.

Why do we lose hair every day?

Daily shedding occurs during the exogen phase of the hair cycle. Losing between 50 and 100 hairs per day is considered normal.

What is the longest stage of the hair growth cycle?

The anagen phase is the longest stage and can last several years. The duration of this phase largely determines how long hair can grow.

Do all hairs grow at the same time?

No. Each follicle follows its own timeline. This means different hairs are always at different stages of the cycle.

How many hairs are on the scalp?

Most people have between 80,000 and 120,000 hairs on their scalp, depending on hair colour and density.

Supporting Your Hair with Herbal Hair

Understanding the hair growth cycle stages is a helpful first step in caring for your hair. When you know how hair grows, it becomes easier to build a routine that supports both your hair and scalp over time.

At Herbal Hair, we focus on botanical ingredients inspired by traditional herbal care. Our formulations are designed to complement everyday hair routines and support the natural environment of the scalp where each strand begins its growth journey.