Reading the Tube: Understanding Hair Color Numbering Systems

The numbers printed on a color tube are not arbitrary, they are a precise shorthand for level and tone that lets colorists formulate consistently. Once you can read the system, you can translate a shade from one line to another and predict exactly how a tube will behave. The codes vary slightly by brand, but the logic is universal. Here is how to decode the tube.

The number before the decimal is the level

The first number tells you the depth on the 1 to 10 level scale, where 1 is black and 10 is lightest blonde. A shade that starts with 6 is a dark blonde, a 4 is a medium brown, and so on. This is the most important number because it sets the depth.

Reading level first, just as you do on the head, keeps your formula grounded. Everything after the decimal modifies tone, not depth.

Numbers after the decimal are the tones

The digits following the decimal or slash describe the tonal direction, with the first being the primary tone and any second being a secondary tone. Common codes include 1 for ash or blue, 2 for violet or iridescent, 3 for gold, 4 for copper, and 6 for red, though they differ by manufacturer.

So a 7.1 reads as an ash level 7, while a 7.43 reads as a level 7 that is primarily copper with a gold secondary. Learning your line's specific key turns the tube into a precise instruction.

• .0 or N: natural or neutral.
• .1: ash or blue.
• .2: violet or iridescent.
• .3: gold.
• .4: copper.
• .6: red.

Why systems differ between brands

Each manufacturer sets its own tonal key, so a .3 in one line may not mean exactly the same thing in another. Always check the brand's shade chart rather than assuming the code carries over identically.

When you switch lines, translate by level and intended tone rather than by code alone. The level number is universal, but the tone digits are dialects of the same language.

Mistakes to avoid

• Assuming a tonal code means the same thing across different brands.
• Focusing on the tone digits and misreading the all-important level.
• Ignoring the order of tones, where the first digit dominates the second.
• Formulating from memory instead of checking the line's own shade chart.

Frequently asked questions

What does the number after the decimal on hair color mean?

The digits after the decimal describe tone, with the first being the dominant tone and any following digit a secondary tone. Common codes are 1 for ash, 2 for violet, 3 for gold, 4 for copper, and 6 for red, though the exact key varies by brand, so check the chart.

Can I substitute a shade from one brand for another?

You can approximate by matching the level and the intended tonal direction, since the level number is universal. The tone codes differ between lines, so rely on each brand's shade chart rather than the number alone, and strand test when switching to confirm the result.

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