How to Use the Time to Sunburn Calculator
Select today's UV Index and your skin type, and this tool estimates roughly how long unprotected skin can be in the sun before it starts to burn. It's a handy gut-check before a beach day, hike, or any long stretch outdoors.
Skin type reflects how sensitive skin is to UV exposure โ fairer skin has less natural melanin and tends to burn faster. At a UV Index of 1, very fair skin (Type I) is estimated to start burning around 67 minutes in, while dark skin (Type V/VI) can take around 400 minutes. As the UV Index rises, that time shrinks proportionally.
This is a simplified estimate for bare, unprotected skin. Actual burn time varies with sunscreen use, shade, reflection off water or sand, and individual skin condition. On days with a UV Index of 6 or higher, reapply SPF 30+ sunscreen every 2 hours and pair it with a wide-brim hat and sunglasses.
Frequently Asked Questions
In theory it scales with the SPF number (SPF 30 is roughly 30x). In practice, sweat, water, and under-application reduce that effect, so reapplying every 2 hours is the safer approach.
Yes โ up to 80% of UV rays pass through clouds and reach the ground. Any day with a UV index of 3 or higher still calls for sun protection, cloudy or not.