SunkatUV index 12: how long can you tan before you burn?
UV 12 is in the extreme band. Here is how long each skin type can stay out, and what it means for tanning.
Short answer: at UV 12, skin starts to redden without sunscreen after about 11 min for very fair skin (type I), 13 min for fair skin (II), 16 min for medium skin (III) and 25 min for olive skin (IV). The Sunkat app keeps a tanning session to 5 minutes per side for fair skin and 8 for medium skin, so you stop well before that.
Minutes at UV 12 by skin type
| Skin type | First redness no sunscreen | Sunkat limit per side | with SPF 30 | with SPF 50 |
|---|---|---|---|---|
| Type I very fair, always burns, never tans | 11 min | 5 min | 7 min | 8 min |
| Type II fair, burns easily, tans a little | 13 min | 5 min | 7 min | 8 min |
| Type III medium, sometimes burns, tans gradually | 16 min | 8 min | 12 min | 14 min |
| Type IV olive, rarely burns, tans easily | 25 min | 12 min | 18 min | 21 min |
| Type V brown, very rarely burns | 33 min | 16 min | 24 min | 28 min |
| Type VI dark brown to black, almost never burns | 55 min | 20 min | 30 min | 35 min |
First redness = minimal erythema dose ÷ (1.5 × 12), using the lower end of each skin type's range. The Sunkat limit is the app's conservative session length per side, capped at 60 minutes. How the numbers are calculated.
Can you tan at UV 12?
Fair skin can redden in 11 to 13 min, which is less time than most people spend getting settled on a beach. WHO's advice at UV 11+ is to avoid being outside at midday and to take every precaution: shade, clothing, hat, sunglasses and SPF 30+. If you want colour, tan before about 10:00 or after 16:00.
When and where you see UV 12
UV 11 and above is normal in Australian and New Zealand summer, in the tropics, and in high mountains, where UV rises about 10% per 1,000 m.
UV changes through the day. The forecast number in your weather app is usually the midday peak, so a morning or late-afternoon session runs at a lower UV and takes longer to reach the same dose.
Other UV levels
Frequently asked
How long does it take to tan in UV 12?
There is no fixed number of minutes, because a tan shows up 2 to 3 days after exposure as your skin makes more melanin, not during the session. What you can control is staying under your burn limit: at UV 12 the Sunkat app's limit is 5 minutes per side for fair skin and 8 for medium skin, well before fair skin starts to redden at about 13 min.
How long until you burn in UV 12?
Without sunscreen, the first redness appears after about 11 min for type I skin, 13 min for type II, 16 min for type III and 25 min for type IV. These are earliest-likely times from the WHO UV index definition and published minimal erythema doses.
Do you need sunscreen at UV 12?
Yes. WHO and national cancer agencies recommend protection from UV 3 upward: shade around midday, clothing, a hat, sunglasses and SPF 30 or higher applied generously and reapplied every two hours.
Can you burn at UV 12 with SPF 50?
Yes. SPF 50 only reaches its label protection with about 2 mg/cm² of sunscreen, roughly a teaspoon for each arm, and most people apply a quarter to half of that. Sweat, water and towels also remove it, so reapply at least every two hours and after swimming.
Know your minutes at UV 12, and every other UV
Sunkat reads the live UV where you are, times each side for your skin type, and tells you when to flip and when to stop. Free on iPhone and Android.
