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Which hair type has the largest diameter?

Hair diameter is an important characteristic that varies across different hair types. Understanding the typical diameter range of different hair types can help guide choices in hair care and styling. In this article, we will examine the diameter of the main hair types and determine which has the largest average diameter.

Hair Diameter Basics

Hair diameter is measured in millimeters and refers to the thickness or girth of each individual strand of hair. Several factors influence hair diameter, including:

  • Genetics
  • Age
  • Health and nutritional status
  • Hair care habits
  • Styling practices
  • Environmental factors

Hair diameter is one of the key properties, along with curl pattern, volume, and density, that defines the major hair types. Measuring the diameter provides insight into the appearance, manageability, and needs of different hair.

Hair Type Classifications

Hair types are commonly grouped into three or four main categories based on visual characteristics:

  • Straight hair – Straight or slightly wavy hair with no real curl pattern.
  • Wavy hair – Somewhat wavy hair with a loose curl pattern.
  • Curly hair – Tight curls or ringlets with a well-defined curl pattern.
  • Coily/Kinky hair – Very tight coils or tight zigzags with a strong curl pattern. Often considered a sub-type of curly hair.

However, other classification systems exist as well. Andre Walker created a more detailed typing system that divides curl patterns into four main types and nine sub-types. This system focuses more on the visual curl pattern rather than the broad categories of straight, wavy, curly, and coily.

Typical Diameter of Each Hair Type

Here is an overview of the typical diameter range for each major hair type:

Straight Hair Diameter

  • Diameter range: 0.06mm to 0.08mm
  • Finer and straighter hair strands
  • Can feel thin or lank if low density

Wavy Hair Diameter

  • Diameter range: 0.07mm to 0.12mm
  • Slightly coarser and fuller than straight hair
  • Medium volume and thickness

Curly Hair Diameter

  • Diameter range: 0.12mm to 0.16mm
  • Much coarser and thicker than straight or wavy hair
  • Can feel dense and full with lots of body

Coily/Kinky Hair Diameter

  • Diameter range: 0.18mm to 0.20mm
  • The thickest and most coarse of all hair types
  • Feels very dense, full, and voluminous

As shown, the diameter ranges increase as the curl pattern tightens. Coily and kinky curly hair has the widest average diameter of all hair types.

Factors Affecting Diameter

While genetics play a major role, other factors can also influence hair diameter within each hair type including:

  • Age – Diameter often decreases with age as hair production slows.
  • Health & Nutrition – Poor health and nutrient deficiencies can lead to thinner hair.
  • Damage – Damage from chemical treatments, heat styling, or the environment can reduce diameter.
  • Products – Some hair products can coat strands and increase diameter.
  • Humidity – High humidity can increase diameter temporarily by swelling the cuticle.

The use of hot tools, chemical processing, and environmental factors tend to have a more significant impact on straight hair diameter compared to curly and coily hair. The dense, coiled structure of kinky hair makes it more resistant to damage-related diameter changes.

Diameter and Manageability

Hair diameter influences hair’s manageability and how it responds to different products and styling approaches. Some key effects of diameter include:

  • Thinner hair can lack volume and be prone to oiliness.
  • Coarser hair may feel drier and be more resistant to shaping.
  • Coarser hair withstands heat styling better than fine hair.
  • Thin hair is easier to damage from styling than thick hair.
  • Coarser strands hold style and shape longer than thin hair.

Understanding your natural hair diameter can help determine the best products and practices for hair care and styling.


Coily and kinky curly hair has the largest diameter range, averaging between 0.18mm to 0.20mm. The highly coiled structure gives it a thick, dense feel and excellent volume. Straight hair has the smallest diameter at 0.06mm to 0.08mm, contributing to a finer, thinner appearance. While genetics determine diameter, factors like age, damage, and styling can also influence thickness over time. Overall, being aware of your hair’s natural diameter is key for choosing products and styles that enhance its natural texture and beauty.

Hair Type Diameter Range
Straight 0.06mm to 0.08mm
Wavy 0.07mm to 0.12mm
Curly 0.12mm to 0.16mm
Coily/Kinky 0.18mm to 0.20mm

With a diameter range of 0.18mm to 0.20mm, coily and kinky curly hair has the largest average diameter of all hair types. Straight hair measures the smallest at 0.06mm to 0.08mm. However, factors like age, damage, and styling can cause diameter to vary within an individual’s natural hair type.

Measuring hair’s diameter provides insight into its texture, manageability, and needs. Thinner hair may require extra gentle care and volumizing products. Coarser strands can withstand more intensive heat styling and hold curls longer. Consulting a stylist to determine your hair type and diameter can guide choices in cut, color, and products.

For curly hair types, understanding diameter can help determine the best products and routines. For example, coily hair with a larger diameter may benefit from deep conditioning and the use of moisturizing creams rather than oils. Those with fine curly hair may need lightweight products to avoid weighing hair down. Diameter and curl pattern work together to influence hair’s overall properties.

While genetics determine our natural hair diameter, how we care for and style our hair impacts its thickness over time. Some practices like frequent heat styling and aggressive chemical processing can permanently alter and thin strands. Protective gentle styling focused on hydration and nourishment helps retain a healthy diameter long-term.

Embracing our natural hair diameter and texture allows us to enhance what makes our hair unique rather than fighting it. There are endless styling possibilities for all hair types when the right customized products and techniques are used. Celebrity examples with stunning coily and curly hair include Viola Davis, Tracee Ellis Ross, and Yara Shahidi.

Understanding diameter’s role leads to better hair health, styling, and appreciation of all hair types. While the differences may seem minute, even tenths of millimeters impact the look, feel, and needs of various hair. Coarser coily hair indeed has the largest diameter, but every type and size has its own beauty. Optimizing routines for our God-given diameter and texture allows our hair’s natural loveliness to flourish.