UV Index Calculator
Turning a UV Index Number Into an Actual Precaution
The UV Index itself is just a number from a forecast, a weather app, or a handheld meter — what actually matters is what that number means for how long you can be outside before skin damage begins. This calculator takes a UV Index reading and translates it into the standard EPA/WHO exposure category, a practical protection recommendation, and an approximate time for unprotected skin to start burning.
Standard UV Index Exposure Categories
| UV Index | Category | Approx. burn time (unprotected) |
|---|---|---|
| 0–2 | Low | 60+ minutes |
| 3–5 | Moderate | 45 minutes |
| 6–7 | High | 25 minutes |
| 8–10 | Very High | 15 minutes |
| 11+ | Extreme | 10 minutes or less |
Actual burn time varies considerably by skin type, altitude, cloud cover, surface reflection (snow and water increase exposure), and time of day, so treat these figures as general guidance rather than precise predictions.
The Categorization Logic
Where This Matters
- Planning outdoor time — checking today's forecast UV Index against these categories tells you whether sunscreen is optional or essential, and how often to reapply.
- Scheduling around peak hours — UV Index typically peaks between 10am and 4pm; on High or above days, shifting outdoor activity outside that window meaningfully cuts exposure.
- High-altitude and reflective environments — UV intensity increases with altitude and near reflective surfaces like snow, sand, or water, so the same forecast number can carry more risk in those settings.
How to Use This Calculator
- Enter the UV Index Value (0–11 or higher) from a forecast or measurement.
- Select Calculate to see the exposure category, protection recommendation, and approximate burn time.
Related Calculations
Check the day's heat risk alongside UV exposure with the Heat Index Calculator, or see current air quality conditions with the Air Quality Index Calculator.