☀️ UV Index Calculator
Enter today's UV index to see the risk category, an estimated time to sunburn for fair skin, and the sunscreen SPF to reach for — a fast sun-safety check for hot, bright days.
🧴 How Strong Is the Sun?
What is a UV Index Calculator?
It takes the day's UV index — the figure your weather app reports — and turns it into practical sun-safety advice: which WHO risk band you're in, roughly how long fair skin can go before burning, and the sunscreen SPF that matches the exposure.
Use it before heading to the beach, the pool, the trail, or a summer event to judge how urgently you need shade, a hat, and sunscreen — and how often to reapply. The burn-time figure is a documented estimate for fair skin that varies with skin type and conditions; it's general awareness information, not medical advice.
❓ Frequently Asked Questions
What is the UV index?
The UV index is an international scale from the World Health Organization that rates the strength of the Sun's ultraviolet radiation at ground level. It runs from 0 upward: 0–2 is Low, 3–5 Moderate, 6–7 High, 8–10 Very High, and 11 or above Extreme. The higher the number, the faster unprotected skin can burn and the more sun protection you need.
How is the time to burn estimated?
This tool uses a common rule of thumb — roughly 200 minutes divided by the UV index — to estimate how long unprotected fair (Type II) skin can be exposed before burning. At UV 8 that's about 25 minutes; at UV 2, about 100 minutes. It's a documented estimate only: darker skin tolerates more, very fair skin less, and altitude, snow, sand, and water all shorten the time.
Which SPF should I use?
As a general guide this tool suggests SPF 15 at Low, SPF 30 at Moderate, SPF 30+ at High, SPF 50 at Very High, and SPF 50+ at Extreme. Whatever the level, apply generously, reapply every two hours and after swimming or sweating, and pair sunscreen with shade, a wide-brim hat, and sunglasses.
When is UV strongest during the day?
UV peaks around solar noon — roughly 10am to 4pm — when the Sun is highest, and it's stronger in summer, at high altitude, and near reflective surfaces like water, sand, and snow. On hot summer days the UV index and the heat often peak together, so sun protection and heat safety go hand in hand. This is general awareness information, not medical advice.