How Do I Read a Hair Colour Number?
The short answer
A colour number reads in three parts: the first digit is the level, the second is the primary tone, and any third digit is a secondary or intensifier tone. A 7.34 is a level seven with a gold primary and a copper secondary, so it reads warmer than a 7.3.
Updated
Anatomy of a colour number
| Digit | Meaning | Example |
|---|---|---|
| First digit | Level | 7 in 7.34 is level seven |
| Second digit | Primary tone | 3 in 7.34 is gold |
| Third digit | Secondary or intensifier tone | 4 in 7.34 is copper |
| Suffix letter | Brand-specific series or base | Brand dependent |
The same number across brands
Tone digit conventions are close to universal across professional colour, but the suffix letters and the base series are not. A level 7 with an ash suffix in one line can carry more violet than the same notation in another.
Before converting a formula to a new line, compare the two shade charts side by side rather than the two names. The number will match; the outcome may not.
Frequently asked
What does a decimal point in a colour number mean?
It separates the level from the tone digits. A colour written 8.1 is a level eight with an ash tone, not a level "eight point one".
What does the letter after a colour number mean?
Usually a brand-specific series marker indicating the base or reflect family. It is not standardised, so always check the brand shade chart.
Keep reading
- What Do Hair Colour Levels 1 to 10 Mean?The level system from black to platinum, with what each step actually looks like on a head.
- What Is the Difference Between Warm and Ash Tones?Gold versus violet, and the reason ash over warm hair reads grey before it reads cool.
- How Do I Switch Professional Colour Lines Safely?Convert level and tone separately, test on a strand, and never convert a corrective in one step.
- Which Developer Volume Lifts How Many Levels?What each volume can and cannot do, and why the standard rule breaks on resistant grey and lightened hair.
Part of Charts in the S2 Academy.