Why Korean base products are numbered 21 and 23 — and what that leaves out
The numbers on Korean base products are an industry convention rather than a standard: 21 is typically a light neutral and 23 a slightly deeper or warmer light-to-medium, with 13 and 17 lighter and 25 upward deeper. Letters such as N, W and C for undertone were added later by individual brands. Nothing guarantees that one brand's 21 matches another's.
What the numbers mean in practice
A great many Korean cushions and BB creams ship in two shades, 21 and 23, and for those products that is the entire range. Around them sit 13 and 17 at the light end and 25 or 27 at the deeper end, though far fewer lines carry them. Some brands append a letter — N for neutral, W for warm, C for cool or pink — and some use their own vocabulary instead. There is no governing body behind any of it, so read the number as a within-brand ordering, useful mainly for choosing between two refills of the same cushion.
Why the range stayed narrow
The convention grew inside a domestic market with a comparatively narrow spread of skin depths and a strong preference for a bright, light finish, and ranges followed demand rather than leading it. Tone-up formulas pushed in the same direction, since a base designed to lighten the look of the skin has little reason to offer deep shades. What resulted is a numbering system that describes a small slice of human skin quite precisely and everything outside it not at all. That is a commercial history, not a technical limitation, and it can be changed by the people who set ranges.
What has changed, and what has not
Ranges have widened, particularly among brands selling heavily abroad, and it is no longer unusual to find Korean base products offered in a dozen or more shades. The deep end is still the thin end. Foundations and concealers generally extend further than cushions do, because a cushion plus its refills multiplies stock-keeping units and brands hedge accordingly. If you are matching deeper skin, expect to shop by individual product rather than by brand, and expect undertone choices to be narrower even where the depth exists.
Matching a shade anyway
Swatch along the jaw and down onto the neck, never on the back of the hand, and look at it in daylight. Give it fifteen or twenty minutes before deciding, because most bases settle warmer or deeper as the film sets. Two shades either side of your match are more useful than one exact hit: mix them as your skin changes through the year, or use the lighter one under the eyes. Tone-up products are a finish rather than a shade, and worn all over skin they were not designed for, they read grey instead of bright.
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✍️ Written & reviewed by the KoreaPlus Editorial team — dermatologist-informed, cosmetic-science researched & source-cited. Last reviewed: 2026-08-23.
General educational information using cosmetic structure-function wording — not medical advice. Always patch-test new actives. © KoreaPlus.