Sun-Safety Tools & Calculators
Free, practical tools for enjoying the sun without paying for it later — time your reapplication, estimate a safe exposure window, measure out the right amount of sunscreen, judge a tan session, gauge vitamin-D exposure, and score your burn risk. Every result is a general estimate, not medical or dermatological advice.
SPF Reapplication Timer
Find out when your sunscreen has worn off. Enter when you applied and whether you've been swimming or sweating to get your next reapplication time — protection fades with water, towels, and time, not the number on the bottle.
UV Index Safe-Exposure Calculator
Estimate how long unprotected skin can stay out before it burns, based on today's UV index and your Fitzpatrick skin type — then see how much longer a given SPF is meant to buy you.
Sunscreen Amount Calculator
Work out how much sunscreen you actually need using the dermatologist's 2 mg/cm² rule — grams, teaspoons, and 'shot glasses' for the body areas you're covering, per application and per day.
Tan Session Time Estimator
Find a sensible time limit for building colour gradually without burning, from the UV index, your skin type, and any SPF — with an honest note on which skin types shouldn't chase a tan.
Vitamin D Sun-Exposure Estimator
Estimate the short midday exposure that may support vitamin D synthesis, from the UV index, your skin type, and how much skin is uncovered — well short of a burn, and no substitute for a blood test.
Sunburn Risk Score
Score today's burn risk from the UV index, your skin type, time outside, SPF, altitude, and reflective surfaces like water, sand, and snow — a quick Low-to-Extreme read before you head out.
Reference
Not a calculator — a data reference built from the same code the calculators run on.