Help with a shipping question!

We're selling lotions and body washes, and just getting our shop off the ground. We have multiple sizes of product, and it's very unclear to us how etsy would calculate the shipping fee if someone were to buy a 2 oz lotion, and two 8 oz lotions. If we set a 2 oz lotion at x.xx charge, and the 8 oz lotion at x.xx charge, would etsy just calculate it at the total of the three, or would it know enough to know that we could fit the 2 oz in with the two 8 oz bottles?

Sorry if this violates any rules, it didn't appear to, but apologies if I'm wrong. Thanks for the help!