Is the number on suncreen an indicator of how long it lasts, how much sun it can take or the percentage of rays it blocks? Or is it something else entirely?
In: Chemistry
SPF is sun protection factor, and its the multiplier of how long you can be in the sun without burning. So if it normally takes you 20 minutes to burn, SPF 30 gives you 600 minutes or 10 hours until you burn. Your sunscreen will need to be re-applied before this point obviously.
You can get the percentage blocked from the equation 100-(100/SPF)
Latest Answers