UV Index Calculator

Estimate UV exposure risk, approximate sunburn time, sunscreen-adjusted time, and sun protection guidance from UV index, skin type, SPF, cloud cover, altitude, reflection, and planned exposure time.

Calculate UV Index Risk

Adjusted UV Index = UV Index × cloud factor × altitude factor × reflection factor
Your result will appear here.

How the UV index calculator works

UV index:
Enter the forecast or observed UV index for the time and location.

Skin sensitivity:
Select a general skin sensitivity level to estimate how quickly sunburn may begin.

SPF and effectiveness:
Enter sunscreen SPF and an effectiveness percentage to create a more realistic protection estimate.

Environment factors:
Cloud cover, altitude, and reflective surfaces adjust the UV exposure estimate.

Why use a UV index calculator?

A UV index calculator is useful for outdoor work, beach days, sports, hiking, gardening, travel, pool time, snow activities, and estimating sun protection needs before spending time outside.

This calculator gives a rough estimate only. Actual sunburn risk varies by skin, medications, time of day, latitude, altitude, cloud type, shade, sweating, swimming, and sunscreen application.

What your result means

Your result estimates UV risk after adjusting for clouds, altitude, and reflection. It also estimates an approximate unprotected burn time and a sunscreen-adjusted time based on SPF and sunscreen effectiveness.

UV index safety tips

Frequently asked questions

What is a high UV index?

A UV index of 6 to 7 is considered high. UV index 8 to 10 is very high, and 11 or more is extreme.

How is burn time estimated?

This calculator uses a simple skin sensitivity baseline and divides it by the adjusted UV index to estimate unprotected burn time.

Does cloud cover eliminate UV risk?

No. Clouds may reduce UV exposure, but UV can still pass through clouds and cause sunburn.

Does SPF multiply safe sun time exactly?

No. Real protection depends on correct application, amount used, sweating, swimming, reapplication, and skin sensitivity.