Sun guides
The sun, explained honestly.
Every guide answers a real question with the published science first, then shows how Soleil turns the answer into something your phone just handles for you.
- Sun safety
How long can you stay in the sun without burning?
How long you can stay in the sun depends on the UV index and your skin type, from ~10 minutes to a few hours. See the table, the maths, and how to track it live.
Read the guide → - UV basics
What UV index is safe? The scale, explained properly
UV index below 3 is low risk for most people; 3 and above calls for protection. Full UV scale table, what each level means for your skin, and when to check it.
Read the guide → - Tanning
What’s the best UV index for tanning?
Tanning starts from about UV 3. Lower UV means slower colour but lower burn risk; UV 8+ mostly adds damage. The honest dermatology position, plus how to pace exposure.
Read the guide → - Sunscreen
How often should you reapply sunscreen?
Reapply sunscreen at least every 2 hours, and immediately after swimming, heavy sweating or towel-drying. Why the rule exists, how much to use, and how to never forget.
Read the guide → - Wellbeing
How much sun do you need for vitamin D?
Around 10–30 minutes of midday sun on forearms a few times a week suffices for lighter skin in summer; darker skin needs longer. Latitude, winter and the honest limits.
Read the guide → - UV basics
Can you tan or burn through clouds?
Yes. Up to 90% of UV passes through light cloud, and broken cloud can even amplify it. Why cloudy-day sunburn is so common and how to check the real UV in seconds.
Read the guide → - Skin
What’s your Fitzpatrick skin type? The 6 types, explained
The Fitzpatrick scale classifies skin I–VI by how it burns and tans. Identify your type with the trait table and see why it changes your sun-protection timing.
Read the guide → - Family
What UV index is safe for kids? A parent’s guide
Children need protection from UV 3, and babies under 6 months should stay out of direct sun entirely. Practical family rules: shade, clothing, SPF, reapply timing.
Read the guide → - Sunscreen
What does SPF actually mean?
SPF is a lab-measured multiplier of how long skin takes to redden under UVB. SPF 30 filters ~96.7%, SPF 50 ~98%, and real-world application changes everything.
Read the guide → - Apple Watch
Apple Watch “Time in Daylight”, explained
Time in Daylight uses the Apple Watch ambient light sensor to estimate minutes spent in ≥1,000 lux. How it works, where to find it, its limits, and how to pair it with UV.
Read the guide →