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Calculate your safe sun exposure time before burning based on UV index and your skin type. Find the minimum SPF sunscreen you need and understand UV index danger levels for outdoor activities, beach trips, and everyday sun protection.
The UV index measures the strength of ultraviolet radiation from the sun. Even on cloudy days, UV can be 80% of full strength. Understanding the UV index for your location and time helps you protect your skin from sunburn, premature aging, and skin cancer — the most common cancer in the US.
The UV Index is a scale from 1 to 11+ developed by the World Health Organization (WHO) and United Nations Environment Programme. It predicts the UV radiation level on a scale and recommends protection measures. UV exposure causes sunburn, premature skin aging, eye damage (cataracts), and skin cancer (melanoma).
| UV Index | Level | Recommendation |
|---|---|---|
| 1-2 | Low | No protection needed for most people, sunscreen optional |
| 3-5 | Moderate | Seek shade near midday, wear sunscreen SPF 15-30+ |
| 6-7 | High | Reduce sun exposure 10am-4pm, SPF 30+, wear hat and shirt |
| 8-10 | Very High | Minimize sun exposure, SPF 50+, UV-blocking sunglasses |
| 11+ | Extreme | Avoid sun exposure 10am-4pm, SPF 50+ essential, full coverage |
The Fitzpatrick scale classifies skin into 6 types based on UV sensitivity. Type 1 (very fair, always burns, never tans) can burn in as little as 10 minutes at UV Index 10. Type 6 (deeply pigmented, rarely burns) has 10× more natural UV protection. Regardless of skin type, no one is immune to UV damage at extreme levels.
| Skin Type | Description | Burn Risk | Tan Ability | Burn Time UV10 |
|---|---|---|---|---|
| Type 1 | Very fair, freckles | Always burns | Never tans | 6-8 min at UV10 |
| Type 2 | Fair skin | Burns easily | Tans minimally | 10-12 min |
| Type 3 | Medium, olive | Burns moderately | Tans gradually | 14-18 min |
| Type 4 | Olive/light brown | Burns minimally | Tans well | 20-25 min |
| Type 5 | Brown skin | Rarely burns | Tans darkly | 30-40 min |
| Type 6 | Deeply pigmented | Never burns | Always tan | 40+ min |
UV radiation peaks at solar noon (12pm-1pm) when the sun is highest in the sky. Approximately 75% of daily UV exposure occurs between 9am and 3pm. UV is also stronger: at higher altitudes (3-5% more per 300m), near reflective surfaces (snow reflects 80% UV, sand 15%, water 10%), in summer vs winter, and at lower latitudes (tropics). Check UV index daily — it varies dramatically with cloud cover and season.