How much capacity of a stainless bottle/plastic tritan bottle would be most popular in USA?

How much capacity of a stainless bottle/plastic tritan bottle would be most popular in USA?

I think the first question would be who you’re looking to market the bottle to.

If you want to sell your bottle to people who plan to use it to stay hydrated while participating in athletic pursuits (sports, hiking, etc), I’d go with a liter, and probably similar dimensions to a standard Nalgene bottle.

If you plan to market your bottle towards office workers and other people with no need to carry a full liter, I’d go with about 300-500 mL, with a narrower shape that would fit well in a car’s cup holder.