In conjunction with Skin Type information and the relevant UV index for that day it indicates the amount of time of safe sun exposure (without the protection of a sun screen) before the skin becomes overexposed to harmful UV radiation and starts to burn.
For example, when the UV index for a particular day reports that a particular skin type can remain exposed to the sun without sun screen for 10 minutes, it means that during the 11th minute the skin will begin to burn. However, if an SPF15 sun screen has been applied before sun exposure, the skin will be protected for 15 times longer from UV radiation - in this case the skin will be protected for 150 minutes (10min x SPF15 = 150min), before it begins to burn on the 151st minute.
Therefore an SPF15 sun screen extends the period for which the skin is safe sun exposure from 10 minutes to 150 minutes. By applying HIMAYA SPF30 sun screen the skin will not burn until after 300 minutes, and so on.
[ 10 (min) x 30 (SPF) = 300 minutes ]