Natalia noticed two bottles of sunscreen side by side at CVS. Initially, it appeared that one was a great deal because it offered 33% more volume at the same price: sort of a reverse Grocery Shrink Ray. Turning the bottle over, though, she read that the bottle had a little less of each of the effective ingredients: about 10% less by volume than the smaller bottle. Doesn’t that mean you have to use more sunblock to get the same effect?

Natalia writes:

I was shopping for sunscreen in CVS yesterday and noticed something peculiar about the Coppertone Sport sunscreen 8oz bottle, and the one that was purporting to be “33% more!” for the same price.

The larger (“more-for-the-same-price”) bottle had precisely 10% less of each active ingredient (except one) than the regular 8oz!

Sure, you still get more of each active ingredient in the larger bottle, but if the overall percentage of the ingredients is smaller, and you put the same amount of sunscreen on as you would with the regular 8oz bottle, you’re getting 10% less protection every time you apply it.

Are you? We aren’t experts in sunscreen chemistry, so we contacted the nice people over at Coppertone. Coppertone is a division of the great big pharmaceutical company Merck, by the way. We explained Natalia’s question about the ingredients. They answered that yeah, the active ingredients are different, but that shouldn’t affect the sunblockiness or the waterproofiness of the product, and doesn’t lower the sun protection factor (SPF) rating.

They answered:

While the two Coppertone Sport Lotion SPF 50 products that you have inquired about differ slightly in formulation, both offer equivalent broad spectrum SPF 50 sun protection and water resistance as well as other characteristics our consumers look for in our Coppertone Sport line of products.

The formulations in each bottle that you have inquired about differ slightly and have different manufacturing dates. Regardless, consumers can use both as directed and be assured they offer the same level of sun protection and water resistance.

In other words, according to Merck, both bottles are just as effective and you shouldn’t need to slather on more just to get the same effect.

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