UV Index Scale

The ultraviolet index scale (UV index scale) is a linear scale used to measure the intensity of ultraviolet radiation (UV) output from our Sun. The UV index scale has a numerical range between 0 and 11+, also known as the UV index (UVI). As the number on the UV index scale increases, so does the sunburn-producing ultraviolet radiation from the Sun. Together with the UV index scale and our local UV index forecasts you can find the best sun protection recommendations. Scroll down to see the official UV index scale and the protection recommendations provided by the World Health Organization, World Meteorological Organization, and the U.S. Environmental Protection Agency.

The Official UV Index Scale

Below is the UV index scale currently in use by many countries around the world, including the United States. In 1994, it was officially adopted and standardized by the World Health Organization (WHO) and the World Meteorological Organization (WMO). The United States replaced its official standards with the WHO/WMO’s in 2004.

UV Index	Risk Category	Recommendations
0 to 2	Low	No protection required. Low from unprotected Sun exposure when the UV index is 2 or less. If you have very light skin and/or burn easily, use a broad-spectrum sunscreen that’s SPF-15 or higher, reapply every two hours. Water, snow, and other reflective surfaces will increase UV exposure.
3 to 5	Moderate	Protection required. Moderate risk from unprotected Sun exposure when the UV index is between 3 and 5. Use a broad-spectrum sunscreen that’s SPF-15 or higher, reapply every two hours. Stay in the shade during midday hours. When outdoors, wear sun protective clothing, sunglasses, and a hat.
6 to 7	High	Protection required. High risk from unprotected Sun exposure when the UV index is between 6 and 7. Use a broad-spectrum sunscreen that’s SPF-15 or higher, reapply every two hours. Stay in the shade during midday hours. When outdoors, wear sun protective clothing, sunglasses, and a hat.
8 to 10	Very High	Extra Protection required. Very high risk from unprotected Sun exposure when the UV index is between 8 and 10. Use a broad-spectrum sunscreen that’s SPF-15 or higher, reapply every two hours. Avoid being outside during the midday hours. When outdoors, wear sun protective clothing, sunglasses, and a hat.
11+	Extreme	Extra Protection required. Extreme risk from unprotected Sun exposure when the UV index is 11 or greater. Use a broad-spectrum sunscreen that’s SPF-15 or higher, reapply every two hours. Avoid being outside during the midday hours. When outdoors, wear sun protective clothing, sunglasses, and a hat.