O.P.

When I look at a bottle of red wine, 750ml, it says 13.5% alcohol.

When I look at a 330ml bottle of Corona it says 4.6% alcohol.

My question is, are those % numbers measured by the bottle or by the 100ml?

For example, is 4.6% of the 330ml Corona alcohol? Or would I get 4.6% alcohol if I drank around 3 bottles of Corona?

Same with the red wine, is 13.5% of the 750ml alcohol?