Each skin type has its own natural protection time, without the appropriate sunscreen you should not stay in the sun longer than your natural protection time. People with extremely sensitive skin can also react more to the sun. Using a cream with sun protection factor (SPF) prolongs the time you can stay in the sun reducing the risk of getting sunburn.
The following formula may be used as a rough guide:
skin’s own protection time x sun protection factor
For example, for fair skin this means; approx 10 mins. x SPF50 = 500 minutes of safe sun exposure*
*This is not the amount of time 1 application of suncream will last, but the maximum amount of time you should spend in the sun per day while reapplying suncream as needed.
This formula applies to all sun protection factors. Once you have reached your sun exposure limit it is advisable not to expose the skin to the sun even though more cream may have been applied.