Category
Sunscreen Basics
How SPF Actually Works (and What the Number Really Means)
SPF isn't a timer and it isn't a percentage of 'strength' — it's a ratio measured in a lab. Here's what SPF 15, 30, and 50 really block, why 'broad spectrum' matters, where the minimal erythema dose comes from, and why the number on the bottle is only half the story.
Chemical vs Mineral Sunscreen: Which Should You Use?
Chemical and mineral sunscreens protect your skin in different ways — one absorbs UV, the other reflects and absorbs it. Here's how each works, their real pros and cons, how they hold up in makeup and water, and how to pick the one you'll actually wear and reapply.
How Much Sunscreen to Apply — The Amount Almost Everyone Gets Wrong
The single biggest reason sunscreen underperforms isn't the SPF you chose — it's using too little. Here's the 2 mg/cm² rule in plain teaspoons and shot glasses, how far a bottle should actually last, and how to cover the spots people always miss.
How Much Sunscreen Each Body Area Actually Needs
'A shot glass for the whole body' is the right rule, but it hides how unevenly that shot glass should be split. Here's the rule-of-nines math behind the Sunscreen Amount Calculator, worked out region by region — face and neck, arms, torso, and legs — in grams and teaspoons.
Sunscreen Reapplication Timing for a Real Day Out
The two-hour rule is a starting point, not the whole story — swimming, sweating, and towelling off all reset the clock differently. Here's a full beach-day timeline, worked out on the SPF Reapplication Timer, showing exactly when each top-up actually falls.
SPF 30 vs 50 vs 100: The Actual Minutes You Gain
How SPF Actually Works explains what percentage of UVB each number blocks. This piece runs the same three SPFs through the site's time-to-burn calculator instead, at a real UV index, across three skin types — and shows why the honest answer to 'should I buy SPF 100' has almost nothing to do with the number itself.
Sun Protection for Babies and Kids: Clothing, Shade, and Sunscreen Basics
Children's smaller bodies and thinner skin change the sunscreen math and shorten the safe-exposure window — and shade and clothing, not sunscreen, are usually the first line of defense. Here's how the site's calculators apply to a child's body, and where this article stops and a pediatrician's advice starts.