Sunscreen Dose
Apply twice as much sunscreen as you think you need. FDA testing calls for about twice as much as most people apply.
To be able to count on the protection listed on the label, apply sunscreen, wait 20 minutes, then apply it again. It takes two to three tablespoons per application to cover exposed adult skin adequately. Look for sunscreens labeled "broad spectrum" or ones that protect against both UVA and UVB rays.