Size of the wine bottle

[Thraz]

If you are talking about the wine aisle at your grocery store, I think the rule of thumb that anything in a jug will not be premium holds. Anything in a large format but regular-shaped bottle (magnum, 1500ml) is also likely to be lower-end.

In a fine wine store, magnums are more likely to hold higher-end wines. Jugs are still lower-end.

Anything in a regular-shaped bottle but larger than 1500ml (e.g. 3 liters or more) is extremely likely to be premium, but those bottles are much harder to find.