Work out beach trip sunscreen amount instantly with clear inputs, formula shown and shareable results.
Dermatology guidance is about 30 grams, roughly a shot glass, for a full adult body, reapplied every two hours, so the total is people times applications times that amount times days. Almost everyone applies about a quarter of the tested amount, which is why real world protection falls well short of the labelled SPF.
Sunscreen needed
grams = people x applications per day x grams per application x days
grams = people x applications per day x grams per application x days. Dermatology guidance is about 30 grams, roughly a shot glass, for a full adult body, reapplied every two hours, so the total is people times applications times that amount times days.
Almost everyone applies about a quarter of the tested amount, which is why real world protection falls well short of the labelled SPF.
Enter number of people, applications per person per day, sunscreen per full body application, days at the beach. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.