Estimate UV radiation intensity from latitude, date, time, altitude, and cloud cover. Get sunburn time warnings and SPF recommendations. Pure frontend, no server uploads.
The UV Index Calculator estimates solar ultraviolet radiation intensity based on latitude, date, time, altitude, cloud cover, and surface albedo. It provides UV index rating, sunburn time warning, and personalized sun protection recommendations. Ideal for outdoor activity planning, travel sun protection, and health management.
Assess UV index before running, hiking, cycling to decide sun protection level and timing.
Understand destination UV index before traveling to tropical or high-altitude areas to prepare proper sun protection gear.
Sensitive skin individuals schedule outdoor time based on UV index to prevent UV allergies and sunburn.
Children's skin is more delicate; parents decide outdoor activities and protection based on UV index.
The UV Index is standardized by WHO. The core calculation uses solar zenith angle (θ), determined by latitude (φ), solar declination (δ), and hour angle (h): cosθ=sinφ×sinδ+cosφ×cosδ×cosh. Solar declination δ=23.45°×sin(360°×(284+N)/365), where N is the day of year. UV index≈12.5×cosθ×altitude correction×cloud correction×ozone correction. Altitude adds ~10% per km. Cloud factors: clear 1.0, few clouds 0.9, partly cloudy 0.75, cloudy 0.55, overcast 0.35. Sunburn time≈200/UV index (minutes, for fair skin).
The UV Index is an international standard measuring sun's UV radiation strength, ranging 0-11+. 0-2 low, 3-5 moderate, 6-7 high, 8-10 very high, 11+ extreme.
This tool estimates UV based on solar zenith angle (from latitude and time), altitude, cloud cover, and ozone attenuation.
UV peaks at solar noon (11:00-13:00 local time). Summer noon UV is typically 2-4 times higher than winter.
UV 3-5: SPF 15+, 6-7: SPF 30+, 8-10: SPF 50+, 11+: SPF 50+ and avoid sun exposure.
UV increases ~10-12% per 1000m altitude. Thinner atmosphere at high altitudes absorbs less UV.