There's not much difference between SPF's, if I remember correctly SPF30 covers about 97%, SPF50 covers 98%
I just use the lower SPF'S because they tend to be thinner and lighter, but with Asian sunscreens they're all the same texture.
But SPF's only refer to UVB rays, they're the rays that cause burning and tanning.
But what you WANT is something that covers UVA rays as well, they're the ones that cause marks, ageing, wrinkles and cancers, and mess that you wont be able to see until 10 years later, the higher
PPD ratings will tell you what sunscreen covers the best
the higher the PPD rating the better, ++++ is the highest, +++ is medium and anything less and kinda useless.
If you want Western Sunscreens look for ones that say "broad spectrum" they'll cover both UVA and UVB
basically:
Asian sunscreens use PPD and SPF
Western Sunscreens use SPF and "broad spectrum"
