Category
UV & Sun Safety
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.
Understanding the UV Index: How to Read It and What to Do
The UV index is a free daily forecast of how fast the sun can damage your skin — yet most people scroll past it. Here's what the 0-to-11+ scale means, where the forecast comes from, what raises it, and the simple actions each band calls for.
Safe Tanning Myths, Debunked
A 'base tan,' the idea that tanning beds are safer, the belief that you can't burn on a cloudy day — the myths around tanning are stubborn and risky. Here's what the evidence actually says, and what a genuinely more cautious approach to time in the sun looks like.
Protecting Your Skin by Type: A Guide to the Fitzpatrick Scale
Not all skin responds to the sun the same way. The Fitzpatrick scale sorts skin into six types by how it burns and tans — here's what each type means for how you protect yourself, how to place yourself on it, and why no type is exempt from sun protection.
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.
What the UV Index Actually Means, Hour by Hour
A single daily UV index number hides how dramatically the risk changes from 7 AM to 1 PM to 7 PM. Here's a worked example running one representative summer day's UV curve through the UV Index Safe-Exposure Calculator, hour by hour, for fair skin.
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.
Vitamin D and Sun Exposure: What the Numbers Assume
The Vitamin D Sun-Exposure Estimator is not a dosing tool and isn't meant to be read as one. Here's what its numbers actually represent — how skin type and how much skin is bare change the estimate — and why a blood test and a doctor, not a calculator, are the only way to know where you stand.
How Long You Can Safely Build Color, by Skin Type and UV Index
Rather than tell everyone the same 'stay under 20 minutes' advice, the Tan Session Time Estimator works out a cautious session cap from your actual skin type and today's UV index — and is upfront that some skin types don't get a tanning session at all, only a burning one.
Your Sunburn Risk Score, Explained With Worked Examples
The Sunburn Risk Score folds UV index, skin type, time outside, SPF, altitude, and reflective surfaces into one 0–100 number. Here's exactly how each factor moves that number, worked out across a beach day, a ski day, and a shaded pool afternoon.