Your skin has two layers of color as far as color analysis is concerned. The overtone is what you see on the surface: how light or dark you are, plus any tan, redness or sallowness of the moment. The undertone is the hue underneath, cool, warm or neutral. A tan changes the overtone. It does not change the undertone, which is why your season usually survives a summer at the beach.
To check your undertone without the surface getting in the way, compare a part of your body that never sees the sun with one that does. The steps are below. The Color Season Quiz asks about undertone separately from depth for the same reason.
Two layers of skin color
Skin color comes from a few pigments. Melanin is the main one: brown-black eumelanin and yellow-red pheomelanin. Blood adds red and blue through hemoglobin, and carotenoids add yellow. How much of each you have, and how they mix, gives your overall color.
Color analysis simplifies this into two readings. Overtone, also called surface tone or skin tone, describes depth and the visible surface color. Undertone describes the temperature that stays constant beneath it. Treating undertone as fixed is a convention of the system rather than a laboratory finding, but it matches what you see when a tan fades.
What a tan changes
Sun exposure, mostly UVB, makes the skin produce more melanin. The result is a deeper overtone, often with a golden or bronze cast on top. Over the following weeks to months, as the outer skin cells are shed, the extra pigment goes with them.
While the tan lasts, three things shift:
- Value. You are a few shades deeper, so very light colors may look paler against you than before.
- Surface warmth. A golden cast can hide pink in cool skin and make it look warmer than it is.
- Contrast. With dark hair, a tan narrows the gap between hair and skin. With light hair, it widens it.
What a tan does not change
The hue beneath the surface stays where it was. Cool skin that tans still reads cool under the jaw and on the inner arm, and still looks best in silver and blue-based colors once the tan settles. Warm skin, tanned or pale, keeps suiting gold and cream. This is also why the sun-reaction question in many quizzes tells you about depth, not temperature: warm vs cool undertone explains the difference.
A tan changes how deep you are, not which side of warm and cool you are on.
The inner-arm check
Compare the inside of your upper arm, which rarely sees sun, with the outside of your forearm, in daylight.
- Same hue, different depth: the forearm is simply darker. Your undertone is unchanged and the tan is only overtone.
- Forearm looks golden, inner arm looks pink: the tan is masking a cool undertone. Judge your colors from the inner arm.
- Both look golden or peach: your undertone is likely warm, tan or not.
Use the inner arm, the jawline and the area under the chin for undertone tests whenever you are tanned.
When a tan moves you to a neighbor
Your season stays, but a deep tan can make a neighboring palette work better for a while. Light seasons often carry slightly deeper colors when tanned. A dark-haired person whose contrast drops in summer may find softer pairings look better than stark ones. Treat these as seasonal borrowings, not a new season, and test your season itself when you are untanned. Sister seasons explains which neighbors share your strongest trait.
Other things that change the overtone
Flushing, broken capillaries, tiredness and self-tanner all change the surface without touching the undertone. Self-tanner in particular adds a golden-brown surface color that can make cool skin test warm. Foundation is matched to the overtone and the visible surface cast, which is why its “warm” or “cool” label can disagree with your season: see foundation undertone vs color season.