Back to blog

The Hair Color Numbering System – Luc Vincent

by Luc Vincent

Have you ever wondered what the numbers on a box of hair colour actually mean? Whether you're at the salon or browsing the drugstore aisle, understanding the hair colour numbering system empowers you to choose the perfect shade with confidence. Here's everything you need to know about what hair colour numbers mean.

How does a hair colour chart work?

Every hair colour is identified by a numeric code made up of two parts, separated by a dot. The number before the dot represents the base colour (also called the level or depth), while the numbers after the dot indicate the tonal reflections. A professional colour swatch chart lets you see each number in action and compare shades before making your choice.

The first number: the level (base colour)

The first number in a hair colour indicates the depth of the shade on a scale from 1 to 10. The lower the number, the darker the colour:

  • 1 — Black
  • 2 — Very Dark Brown
  • 3 — Dark Brown
  • 4 — Medium Brown
  • 5 — Light Brown (Chestnut)
  • 6 — Dark Blonde
  • 7 — Medium Blonde
  • 8 — Light Blonde
  • 9 — Very Light Blonde
  • 10 — Extra Light Blonde (Platinum)

For very pale blonde, white, or grey hair beyond level 10, there is no official numbering — these hair types contain virtually no natural pigment left.

Hair colour numbering system chart — tone levels from 1 (black) to 10 (platinum blonde)

The second number: tonal reflections and what they mean

A dot is always placed before the number that designates the natural or artificial reflection. This second number after the dot indicates the undertone or reflection of the colour:

Hair colour reflection chart — number-to-colour correspondence for tonal reflections
  • .1 — Ash (Blue)
  • .2 — Iridescent (Violet)
  • .3 — Gold (Yellow)
  • .4 — Copper (Orange)
  • .5 — Mahogany
  • .6 — Red
  • .7 — Green (Matte)

Warm reflections (yellow, orange, mahogany, red) complement bronzed skin tones or complexions with yellow or peach undertones, while cool reflections (blue, violet) flatter fair or rosy complexions.

How to read a hair colour number: real-world examples

Now that you understand both parts of the system, let's see what happens when you combine a base colour with a reflection:

  • A colour marked 6.3 gives a dark blonde with a golden reflection.
  • A colour marked 4.6 gives a medium brown with a red reflection.
  • A colour marked 1.1 gives a black with an ash-blue reflection.

Keep in mind that the higher your first number, the more visible and dominant the reflection will be. For example, a 6.6 will look much more vibrant red than a 4.6, which will read more brown than red. Once the level exceeds 6, reflections have a particularly dominant effect on the final result.

In summary: the structure of a hair colour number

  • The first number indicates the level. Example: 5 = light brown.
  • The second number (after the dot) designates the primary reflection. Example: .3 = gold.
  • A third number may be added for a secondary reflection. Example: .34, where the 4 = copper.

This code would give a light brown with gold and a subtle copper undertone (5.34). Before choosing your shade from the Luc Vincent professional colour line, always consult the manufacturer's swatch chart, as numbering can vary slightly from brand to brand.

The role of zero in the numbering system

In some cases, certain brands add a 0 to soften or intensify a reflection:

  • Placed before the reflection number, the 0 softens it. For example, 5.04 would give a light brown that is slightly copper.
  • Placed after the reflection number, the 0 intensifies it. So 5.40 would give a light brown that is intensely copper.

To indicate very intense reflections, the number can also be doubled. For instance, .44 represents an intense copper reflection, and .66 represents an intense red.

Complementary colours on the colour wheel in hair colouring

To truly understand hair colour, you need to grasp a fundamental principle of colour theory: complementary colours on the colour wheel cancel each other out. This is the principle colourists use to neutralize unwanted tones.

Here are some handy memory tricks to remember complementary colour pairs:

  • Blue (.1) cancels out orange (.4) — Think of your beach vacation: the ocean and the sun!
  • Violet (.2) cancels out yellow (.3) — Think of Easter colours.
  • Green (.7) cancels out red (.5 or .6) — Think of Christmas colours.

How to neutralize an unwanted tone

With this knowledge, it's easy to find the colour that cancels an unwanted reflection. If you ask for golden highlights, know that yellow will automatically be present in your colour formula.

For example, if your current colour is an 8.3 and your hair looks too golden, simply add a small amount of 8.2 to your next colour mix (roughly one part 8.2 to three parts 8.3). The violet will "extinguish" the yellow, since opposite colours on the colour wheel cancel each other out.

This is exactly why, for blonde hair that's turned too yellow or white hair that yellows over time (often caused by oxidation), a specialized purple or blue shampoo is recommended. The Sans Yellow line by Luc Vincent