Understanding the Hair Color Numbering System

 Your hair is as unique as you are, and it deserves a tailored approach to ensure it looks and feels its best. Whether you're considering a new hair color or just want to maintain your current shade, understanding the hair color numbering system is essential. In this comprehensive guide, we will delve into the intricacies of this numbering system and how it ties into personal hair care.


The hair color numbering system is a standardized method used by the hair care industry to classify hair colors. It helps both consumers and professionals choose the right hair color products and treatments. This system typically consists of a combination of numbers and letters, and each part has a specific meaning.


The Number: Hue

The first part of the hair color number represents the hue or the color family. It ranges from 1 to 10, with 1 being the darkest (black) and 10 being the lightest (palest blonde). Here's a breakdown of the number scale:

  • 1: Black
  • 2: Very dark brown
  • 3: Dark brown
  • 4: Medium brown
  • 5: Light brown
  • 6: Dark blonde
  • 7: Medium Blonde
  • 8: Light Blonde
  • 9: Very light blonde
  • 10: Palest Blonde

This number tells you the underlying color you can expect from a specific hair dye or treatment. 


The Decimal: Tone

The decimal part of the hair color number is crucial for understanding the tone of the hair color. It indicates the warmth or coolness of the shade. Even numbers (e.g., 4.0, 6.0) are cool tones, often described as ashy or cool, while odd numbers (e.g., 4.1, 6.1) are warm tones, often described as golden or warm.

For example, if you choose a hair color with the number 6.3, you can expect a warm, golden blonde. However, if you go for 6.0, you'll get a cool, ashy blonde.


The Letter: Reflect

In some hair color systems, you may also find letters used to describe the reflection of the hair color. These letters can indicate special characteristics like extra ashiness (A), extra warmth (R), or even a combination of both (AR). They provide further customization to the hair color, allowing you to choose a shade that best suits your personal preferences.

For instance, a hair color labeled as 5.3AR would be a medium brown with a warm, golden tone and hints of ashiness.


How to use the Hair Color Numbering System for choosing a color.

Now that we've decoded the hair color numbering system, let's explore how it ties into personalized hair care and preferences when choosing a color.


Finding Your Perfect Shade

Whether you're going for a subtle change or a dramatic transformation, understanding the hair color numbering system helps you select a shade that complements your skin tone, style, and personality. A professional colorist can also assist in determining the most flattering hue for your hair. Here are some tips to keep in mind when choosing a color:


 There are generally three main categories of skin tones:

  • Cool: If you have cool undertones, you're likely to have fair or pale skin with pink or bluish undertones. Shades that work well for cool-toned individuals include ashy blondes, cool browns, and jewel-toned reds.
  • Warm: Warm undertones are characterized by peachy, golden, or yellowish hues in the skin. People with warm skin tones often look great with warm hair colors, such as honey blondes, golden browns, and coppery reds.
  • Neutral: Some individuals fall into the neutral category, meaning they have a balanced mix of cool and warm undertones. This allows for more flexibility in choosing hair colors. Neutral-toned individuals can pull off a wide range of shades.


Minimizing Damage

When you dye your hair, it's essential to consider the condition of your hair. The hair color numbering system often includes a separate developer or "developer strength" number. The developer is the oxidizing agent that activates the hair dye and determines how much lift and color deposit will occur. Developer strength is typically represented as a volume, such as 10, 20, 30, or 40 volume. The higher the volume, the more lift and color change it provides. Understanding the developer's strength is essential for achieving the desired result, especially when you need to lighten or darken your hair.

  • 10 Volume: This is the lowest strength and is often used for toning, depositing color, or darkening hair slightly.
  • 20 Volume: Commonly used for lifting one to two shades and is suitable for gray coverage.
  • 30 Volume: Provides more lift and is used for lightening hair by two to three shades.
  • 40 Volume: Offers maximum lift and is used for dramatic lightening, but it can be harsh on the hair and is typically used by professionals.


The hair color numbering system can also specify whether a product is permanent, semi-permanent, or demi-permanent. This information is essential for understanding the longevity and commitment level of the color.

  • Permanent: These hair colors use a developer to lift and deposit color, and they last until your hair grows out. They provide the most significant color change.
  • Semi-Permanent: These colors don't use a developer and typically last through several washes. They're ideal for adding temporary color or enhancing your natural shade.
  • Demi-Permanent: These colors use a low-volume developer and last longer than semi-permanent but less than permanent colors. They're suitable for subtly altering color or adding shine.

The hair color numbering system can include letters or symbols that represent certain ingredients or benefits in the formula. For example:

  • C: Conditioning formula that includes ingredients to nourish and hydrate the hair.
  • M: Moisturizing formula that provides extra moisture to prevent dryness.
  • R: Repairing formula that helps to strengthen and repair damaged hair.
  • V: Vibrant or intense color formula, which is often used for fashion colors and vivid shades.

Understanding these symbols can help you choose a formula that aligns with your hair's specific needs and your desired outcome. For instance, if you have dry and damaged hair, a formula marked with "C" and "R" may be an excellent choice. Some products in the system are designed to minimize damage and nourish your hair while coloring. Look for labels that mention features like "conditioning," "moisturizing," or "repairing" to ensure you're making a gentle choice for your hair.


The hair color numbering system is more than just a set of numbers and letters; it's a tool that empowers you to personalize your hair care. Understanding the hue, tone, and reflection of your chosen hair color allows you to make informed decisions, minimize damage, maintain your color, and correct any mistakes. With this knowledge, you can confidently embark on your hair coloring journey and enjoy vibrant, healthy, and beautifully personalized locks, however, it's always best to consult a professional who has both knowledge and experience when you are applying the color to your hair. Happy coloring!

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Elia Seyfried

Elia enjoys a good book, is a hair care enthusiast, loves to write, and hopes to inspire and educate through her work.

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