To ask this question about sunscreen and foundation with built in SPF

[Butterfly98]

I use No7 SPF 15 sunscreen on my face everyday followed by No7 light foundation which also has SPF 15. This sounds like a really silly question but does that mean SPF doubles up to 30 or does it stay at 15? I asked at the No7 counter today and the assistant didn't know either!

I think it'll always just be factor 15!

It will always be 15. It doesn't double the SPF.

It would stay at 15, but realistically you aren't going to use enough of the foundation to make any difference to the SPF at all, so if you only used the foundation and not the sun screen you wouldn't really be protected at all.

"But suffice it to say that if you mix sunscreen, the maximum SPF you'll get is the higher of the two you started with," she said. "And you'll likely end up diluting it instead.

www.washingtonpost.com/gdpr-consent/?destination=%2fnews%2fspeaking-of-science%2fwp%2f2016%2f06%2f20%2fdear-science-what-does-sunscreen-spf-mean-and-what-happens-if-you-mix-them%2f%3futm_term%3d.988b13140fb0&utm_term=.79646ecbfb68

No it doesn’t double, it would still be spf 15.

Thanks all, I thought it probably would stay at 15!