UV TrackerThe six Fitzpatrick skin types — and what comes after
What the scale is
Dermatologist Thomas Fitzpatrick introduced the scale in 1988 to classify skin by its reaction to sun exposure — how easily it sunburns and how readily it tans — rather than by color alone. It remains the most widely used skin-typing system in dermatology and sun-safety guidance, including in the Minimal Erythemal Dose (MED) values behind UV Tracker's safe sun time tables.
The six types
| Type | Sun reaction | Typical MED (J/m²) |
|---|---|---|
| I | Always sunburns, never tans | 200 |
| II | Sunburns easily, tans minimally | 250 |
| III | Sometimes sunburns, tans gradually | 350 |
| IV | Rarely sunburns, tans easily | 450 |
| V | Very rarely sunburns, tans darkly | 600 |
| VI | Deeply pigmented, almost never sunburns | 1000 |
How your type is assessed
Traditionally, type is self-reported through a short questionnaire about how skin responds to a fixed amount of summer sun. That works well as a starting point but is subjective — instrument- and photo-based measurement offer a more repeatable estimate, which is why they're an active area of research.
ITA° and CIELAB
A more objective route measures skin color in the CIELAB color space (lightness L*, and the yellow-blue axis b*) and derives the Individual Typology Angle (ITA°) from them. Smartphone-based skin colorimetry — measuring color from an ordinary phone photo under known conditions — has been validated against clinical instruments with good reliability. Recent work has also explored automated image-classification approaches for mapping photos to Fitzpatrick categories more consistently than manual assessment.
Beyond Fitzpatrick: the Monk scale
Because Fitzpatrick's six categories were built around sun reaction, not the full range of human skin tones, they can under-represent darker skin. The Monk Skin Tone scale, with ten graduated tones, was developed to represent skin color more evenly. Research mapping ITA° to both scales has found strong agreement with Monk classifications, with Fitzpatrick alignment somewhat less consistent — a reminder that any single scale is an approximation.
What UV Tracker does
The app measures your forearm's color from a single photo, computes ITA°, and fuses that measurement with your own self-reported answers for a type estimate with a confidence figure — combining the objective and subjective methods rather than relying on either alone. See how the app works for the full picture, or the safe sun time tables for what your type means in minutes.
UV Tracker measures the UV where you stand — sky scan for local conditions, one photo for your skin type, and your safe sun time on one card. Free forever.
References
- Fitzpatrick TB. "The validity and practicality of sun-reactive skin types I through VI." Archives of Dermatology, 1988.
- Ulrich P, Zink A, Biedermann T, Sitaru S. "Beyond Fitzpatrick: automated artificial intelligence-based skin tone analysis in dermatological patients." npj Digital Medicine, doi:10.1038/s41746-025-01770-4.
- Crocker Garcia G, Khan MN, Alam A, Obregon J, Abuhmed T, Huh E-N. "FiSC: A Novel Approach for Fitzpatrick Scale-Based Skin Analyzer's Image Classification." IEEE Access, doi:10.1109/ACCESS.2025.3547573.
- Ouyang H, et al. "Bridging Accessibility and Precision: Evaluating the Reliability and Validity of a Smartphone-Based Skin Colorimeter." Clinical, Cosmetic and Investigational Dermatology.
UV forecast data in the app: Open-Meteo.
This article is general information, not medical advice. Sun-exposure estimates are approximations. If you have concerns about your skin, or a history of skin cancer in your family, see a doctor or dermatologist.