Skin Type Cutoffs, Explained: What a 434-Adult Korean Data Bank Used for Sensitivity, Hydration and Oiliness, and Why the Numbers Are Not Universal
Most skin-type quizzes sort people into oily, dry, combination, normal or sensitive by how skin feels. A Korean research group asked what those labels would look like if instruments defined them. Their 2022 paper reports actual cutoffs. This guide sets out the numbers and why they are not a personal pass or fail line.
Where the numbers come from
The paper is by Seo and colleagues, in the Journal of the European Academy of Dermatology and Venereology, 2022. It used the 2018 International Skin Characteristics Data Bank Project of the Foundation of Korea Cosmetic Industry Institute: 434 healthy South Korean adults, each measured with eight devices, including a Tewameter, pH meter, Corneometer, Sebumeter and Cutometer.
Five categories, not one label
The system has five categories: sensitivity, hydration, oiliness, elasticity and skin tone. It is similar in spirit to our Baumann 16-type guide, except that devices supply the scores. Someone can be oily and dehydrated at once, because the two are measured separately.
The cutoffs the authors report
- Sensitive: TEWL over 18.0 g/m2/h, or surface pH over 5.45
- Dehydrated: Corneometer below 47.17 arbitrary units
- Oily: Sebumeter above 70 micrograms per square centimeter
- Loose: Cutometer R2 below 0.68
The abstract gives no numeric cutoff for skin tone and does not name the measurement site, so check the full paper before comparing any reading.
Why the lines depend on the group
The authors divided the measurements into tertiles to set reference points, so the lines come from the spread of this group. That is our reading, not the paper's claim, but another population, age mix or device model would likely draw different lines. The stated aim was reference values for the Korean population.
What each device reads
- Tewameter: water leaving through the skin surface
- pH meter: surface acidity, a topic in our cleanser pH guide
- Corneometer: outer-layer hydration in arbitrary units
- Sebumeter: oil on a tape, as in our Sebumeter mismatch article
- Cutometer: how skin springs back after suction, summarized as R2
What other Korean studies add
Baek and colleagues (International Journal of Cosmetic Science, 2011) measured the cheeks of 103 women aged 20 to 59 under controlled conditions. A clinician graded 6 as very dry, 29 as dry and 68 as normal. A 2025 paper in Frontiers in Cellular and Infection Microbiology combined measurements, a Baumann survey and microbiome data from 950 Korean subjects, and split women into three age groups.
What this means when you shop
You will not own these devices, but the framework helps. Ask separate questions. Does skin sting or flush with new products? That is sensitivity, and our sensitive versus sensitized guide explains why a label cannot settle it. Tight after cleansing suggests hydration. Midday shine suggests oil. Match texture to each answer.
Limits to keep in mind
- The sample was healthy South Korean adults, so the cutoffs may not transfer
- A threshold sorts a measurement, it is not a diagnosis
- One reading is a snapshot, since room conditions change results
This article is general information, not medical advice. Skin-type categories describe measurements, not conditions. Patch test any new product and consult a dermatologist about skin concerns.
All content is fact-checked under our editorial standards.