How to find your undertone

Undertone · five tests · warm, cool, neutral, olive

Undertone is the most useful thing you can know about your colouring, and it's also the thing almost everyone gets wrong first time round. Not because the tests are bad – because nobody tells you when they stop working. Warm indoor light turns cool skin warm. A tan wipes the answer out completely. Olive skin fails the gold-versus-silver test by looking perfectly fine in both, which is maddening. So here are the five tests worth doing, what each one is actually measuring, and the exact moment each one will lie to you.

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Close-up of the inside of a wrist in daylight, veins reading distinctly blue beneath fair skin

Undertone and skin tone are different things

Skin tone is how light or deep your skin is. Undertone is the temperature sitting underneath it – the quiet cast that stays put whether you're pale in February or three shades darker in August. They move independently, which is why knowing you're 'fair' tells you nothing about warm or cool, and why two people with identical foundation depth can need completely different shades of it.

There are four answers here, not two. Warm leans golden, peachy or yellow. Cool leans pink or blue. Neutral sits in between without committing to either. And olive has a green or grey cast that cuts straight across the whole warm/cool question. Olive is the one that gets misdiagnosed most, usually filed as 'neutral' by people who've run out of other options.

One more thing worth separating: overtone is the colour you see on the surface, undertone is what sits beneath. Redness from irritation, a flush, healing spots – all of that is overtone. It'll confuse every test below, which is why you do this on calm, bare skin.

What the vein test actually looks like

All three of these are real readings, and the third one is the reason this test gets over-trusted. Inside of the wrist, daylight, no filter.

Inside of a wrist in daylight, veins reading distinctly blue-violet — Blue or purple points cool.

Inside of a wrist in daylight, veins reading olive green — Green or olive points warm.

Inside of a wrist in daylight, veins faint and hard to read between blue and green — Faint and hard to call. Extremely common, and it's why this test can't be the decider.

The five tests

Do these in daylight, near a window, bare-faced, hair pulled back. Indoor bulbs are warm and they'll push every single answer toward warm. Answer what you actually see rather than what you expect, and use the middle option freely — half these tests genuinely fail on some people.

01
The white test
most reliable
Optic-white paper next to your face, then a warm cream sheet. The most reliable of the five, because it takes colour out of the comparison almost entirely.
02
The metals test
most reliable
Gold on one wrist, silver on the other, in daylight. Look at the skin next to the metal, not the metal.
03
The vein test
Inside of the wrist, in daylight. Supporting evidence only — vein colour is partly skin thickness, so do not let it outvote the two above.
04
The sun test
How your skin behaves over a week outdoors, not one afternoon.
05
The olive check
overrides the rest
Jawline and neck, daylight, mirror. Olive sits off the warm/cool axis, so if this one is a yes it beats everything above — that is exactly why olive keeps getting filed as “neutral”.

Your reading

Answer all four tests to get a reading. 0/4 so far. The olive check on its own is enough if it is a clear yes.

Every test above is a manual stand-in for something siOsi measures directly, and it returns olive as a real answer rather than rounding it to neutral. One photo also gives you your season, your contrast level, and the makeup labs that catch a base fighting your undertone.

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The two worth trusting most

These two carry more weight than the veins or the sun, because they compare your skin against a fixed reference instead of asking you to judge it in isolation. If they agree with each other, go with them.

Two sheets of paper on a grey surface, bright optic white on the left and warm cream ivory on the right — The white test. Optic white left, cream right — hold each beside your face and watch which one makes your skin look even.

A forearm on a grey surface wearing a plain yellow-gold bangle beside a plain silver bangle — The metals test. Look at the skin next to the metal, never at the metal itself.

Where each test falls apart

This is the part nobody publishes. Every test above has conditions that break it, and if your results are contradicting each other, one of these is almost certainly why.

Indoor light ruins everything: Household bulbs are warm, usually around 2700K. Under them, cool skin reads warm and green veins show up where there are none. This one factor causes more wrong answers than all the others combined. Daylight, near a window, no exceptions.
A tan wipes the answer out: Sun exposure lays down melanin and shifts your surface warm no matter what your underlying temperature is. Test at your palest, or test the skin on your inner upper arm where the sun rarely gets to.
Olive skin passes both metals: The gold-versus-silver test assumes a warm/cool axis. Olive sits off that axis, so both metals look fine and the test hands back "neutral". That's why so many olive people get told they're neutral, then find neutral foundations still go grey on them.
Veins are anatomy as much as temperature: Vein colour is partly about how light scatters through the skin above them, which depends on skin thickness and depth. On deeper skin tones veins are often hard to see at all. That makes this the least reliable of the five, which isn't a reason to skip it, just a reason not to let it outvote everything else.
Redness pretends to be cool: Rosacea, irritation, a post-workout flush, healing blemishes – all of that adds pink to the surface, and all of it is overtone. Test on calm skin, and if your face runs reactive, judge from your inner arm or jaw instead of your cheeks.
Dyed hair breaks the room, not the test: Hair colour doesn't change your undertone, but it does change what looks good next to your face, which makes judging yourself harder. Stick to skin, and remember your season describes your natural colouring. The dye is a costume, and the test can see through it.

What it actually changes

Undertone isn't trivia. It decides whether a product disappears into your skin or just sits on top of it.

Foundation: Shade codes carry it. N is neutral, C or R leans cool and pink, W or D leans warm and golden. A shade that matches your depth but fights your undertone goes ashy if it's too pink and muddy if it's too gold. Match undertone first, depth second.
Concealer: Under-eye darkness is usually blue or purple, so it wants a peach or orange corrector regardless of your undertone. Your undertone governs the concealer you set it with, not the corrector underneath.
Blush: Warm undertones look best in peach, coral and warm terracotta. Cool undertones want true rose, berry and cool pink. Olive usually looks best in a slightly muted brick-leaning pink rather than anything clean and bright.
Lipstick: The red test is the fastest read in all of makeup. Orange-leaning reds flatter warm undertones, blue-leaning reds flatter cool. If a red makes your teeth look yellow, it's fighting you.
Metals and jewellery: Gold on warm, silver and platinum on cool, either on neutral. Olive usually looks best in a soft or antiqued gold rather than a bright yellow one.
Your season: Undertone is one of three axes that place you in a colour season. The others are value (how light or deep) and chroma (how bright or muted). Getting undertone right narrows twelve seasons down to about four before you have looked at anything else.

If the tests disagree

Count them, then weight them. The white test and the metals test are the most reliable of the five. The vein test and the sun test are supporting evidence. If white and metals agree with each other, go with them even when the veins are saying something else.

If they split three ways, you're most likely neutral or olive, and the difference between those two really matters. Neutral skin looks fine in most things and better in some. Olive skin looks actively wrong in certain foundations, going orange or grey on you at the correct depth. If foundations keep failing on you in a way that changing depth never fixes, you're probably olive rather than neutral.

And landing on neutral is not a failed diagnosis. It means your palette is wider than most people's, and the useful information just moves over to your value and contrast levels instead.

“Most people have predominantly yellow undertones in the skin – not pink as many people think. It’s safest, when choosing a foundation, to err on the yellow or golden side, not the blue-pink side.”

Carole Jackson · Color Me Beautiful, 1980

Or have it measured

Every test above is a manual stand-in for something siOsi measures straight from a photo. You get your undertone back as one of four values: warm, cool, neutral or olive. That last one matters here, because olive is exactly what the DIY tests systematically miss and what most tools don't report at all.

Undertone is one of fifteen labs, though, and the others are where this stops being theory. siOsi doesn't only name your undertone – it checks whether the makeup you're already wearing is fighting it. Oxidation catches foundation that turns orange on you a few hours in, which is almost always an undertone mismatch rather than a bad product. Flashback catches the base that looks fine in the mirror and grey-white in photos. Coverage tells you whether you're using more product than your skin needs. Those are the symptoms people usually blame on their foundation when the real culprit is temperature.

You also get your season and your contrast level separately, plus geometry reads on your lips, eyelids and face shape, which govern placement rather than shade. When undertone and season agree you can stop second-guessing. When they don't quite line up, that disagreement is information too, and it usually means you're near a boundary.

Free, no signup, one photo. Then come back and check it in daylight, because your own eyes next to a window are still the honest arbiter.

Free color analysis The 12 seasons

Answered

What is the most reliable undertone test?

The white test: optic white paper against warm cream, in daylight, next to your face. It takes colour out of the comparison almost entirely, so it separates warm from cool more cleanly than the vein test does. The metals test is a close second.

Why do my vein test and jewellery test disagree?

Usually lighting. Warm indoor bulbs make veins look green and skin look golden, which pushes both tests warm, though the metals test resists it better than the vein test does. Redo both near a window. If they still disagree, you are likely neutral or olive.

Can my undertone change?

No. Your surface colour changes constantly with tanning, seasons, flushing and medication, but the cast underneath does not. What changes is how easy it is to read, which is exactly why you test at your palest and on calm skin.

How do I tell olive from neutral?

By how foundation fails on you. Neutral skin looks fine in most correct-depth foundations. Olive skin goes visibly orange or grey at the correct depth, and no amount of shade-depth tweaking fixes it. If that is your experience, you are olive.

Does undertone decide my colour season?

It is one of three inputs. Undertone gives you temperature, then value (light versus deep) and chroma (bright versus muted) do the rest. Undertone on its own narrows twelve seasons to roughly four.

Can I find my undertone with deep skin?

Yes, though the vein test is much less useful because veins are harder to see. Lean on the metals test, the white test and how foundations behave on you, since those work at every depth. Deep skin spans the full range of undertones, olive very much included, and it gets missed a lot.