How colour theory applies to hair
Primary colours are red, yellow and blue. Mix two and you get a secondary: orange, green or violet. Each secondary sits opposite the primary it doesn't contain. Put opposites together in the right amounts and they cancel into a neutral brown-grey. On hair, that neutral reads as "natural" or "beige".
Which colour cancels which in hair
| Unwanted tone | Neutralise with | Where you'll see it on products |
|---|---|---|
| Yellow | Violet | Purple shampoo, violet or pearl toners, .2 shades |
| Gold (yellow-orange) | Blue-violet | Pearl, silver or "cool" toners |
| Orange | Blue | Blue shampoo, ash toners, .1 shades |
| Red-orange | Blue-green | Blue-ash or ash with a green lean |
| Red | Green | Matte or green-based shades and correctors |
The interactive wheel shows all twelve tones and their opposites.
How to tell what undertone your hair has
- Use daylight and a white background. A white towel behind the hair helps.
- Compare with something familiar. A lemon is yellow, a ripe apricot is orange and a tomato is red. Which is closest?
- Check different areas. Roots, mid-lengths and ends often show different undertones because they've had different treatment.
- Take a photo without filters. Phone cameras often warm or cool images, so turn off beauty modes.
How much corrector to use
Neutralising takes balance. A little opposite tone softens warmth. Too much overshoots: violet on very pale blonde can leave lilac, blue on light blonde can leave a grey-blue or green cast, and green on red can look muddy. Start with the mildest option, such as a toning shampoo used once or twice, before reaching for a stronger toner.
A neutraliser can't lighten hair. If your hair is level 7 orange and you want level 9 beige, toning orange away won't get you there. You need to lift to level 9 first, then tone the remaining yellow.
When you want warm undertones
Undertones aren't always a problem. Copper, gold and red shades deliberately use the warm side of the wheel. If you're going warmer, the underlying pigment works with you, and results often look richer and fade more gracefully. Use the skin tone guide to see whether warm or cool shades suit you.
Mixed undertones: orange roots, yellow ends
Hair rarely shows one clean tone. A level 7 might be orange at the root and yellow on sun-lightened ends. Colourists often apply different toners to different zones in that case, or choose a shade between the two opposites, such as a blue-violet. If in doubt, a strand test on each zone will tell you more than any chart. For product choices, see how to fix brassy hair.
Undertone questions
Why doesn't purple shampoo work on my orange hair?
Purple is the opposite of yellow. Orange needs blue, so a blue shampoo or ash toner works better.
Can too much toner give hair a colour cast?
Yes. Violet on very pale blonde can leave lilac, blue can leave a grey-blue or green cast, and green on red can look muddy. Start mild.
Are warm undertones in hair bad?
No. Copper, gold and red shades use the warm side on purpose, and they often fade more gracefully because the underlying pigment works with them.