Supergoop! Everyday Sunscreen With Cellular Response Technology Spf 50, 18 Fl. Oz.

Q: I'm deciding between sizes ... how long is the large size 'good' for, meaning what is the approximate length of time between until expiry?

I would recommend the large size - it's what I wish I had gone with. This sunscreen is amazing and at 18oz is 7.5% larger than the small version. The small one lasted me about two weeks of vigorous use (river trips and two pool days, along with my regular every-day use). I'd say you could probably get about 3 months of use out of the larger one, if it's just you using the sunscreen.