Sun-Safety Tools & Calculators
Free, practical tools built on the official advice: time your reapplication, read the day’s UV category, measure out the right amount of sunscreen, and see what the NIH says about vitamin D. None of them gives a time in the sun. General information, not medical advice.
SPF Reapplication Timer
The latest time to put more sunscreen on, on the FDA's rule: at least every two hours, and more often if you're sweating or swimming. Enter when you applied, what you're doing and the label's water resistance.
UV Index Category Checker
Put today's UV index in its WHO category (a fraction always rounds up) and read what WHO and the EPA say to do at that level, word for word.
Sunscreen Amount Calculator
How much one coat takes at the 2 mg/cm² density SPF is tested at, in grams, fluid ounces, teaspoons and shot glasses, never below the FDA's one ounce for a whole body.
Vitamin D and the Sun: What the NIH Says
Tick what applies to you and read the NIH Office of Dietary Supplements' own words on vitamin D from the sun, food and a blood test. No sun-exposure time and no supplement amount.
Sunburn Risk Category
Add what WHO says water, sand, snow and altitude add to the forecast, and read the category for the UV you will actually get, with the WHO and EPA advice.
Reference
Not a calculator — a data reference built from the same code the calculators run on.