This article seems to say that getting a base tan helps to get 3-4 SPF, so your time-to-sunburn increases up to 4 times. https://www.health.harvard.edu/blog/pro

This article seems to say that getting a base tan helps to get 3-4 SPF, so your time-to-sunburn increases up to 4 times. https://www.health.harvard.edu/blog/problem-tanning-myth-base-tan-2017041211528 https://www.health.harvard.edu/blog/problem-tanning-myth-bas... I would not rely on it overall tough.