I used to just say 6 syns for a beer. No idea if I was right or not! Post in the syns forum with all the info and I'm sure someone can help - and then let us know!!
It all depends on the alcohol content! It would wouldn't it . . . as this affects the sugar content and hence the calories. Working on 330ml bottles the average SYNS are roughly as follows: Stella / Grolsch = 7.0 Budweiser = 7.0 Bud Light = 5.5 Becks = 6.0
Here in France we have some really good alcohol-free bottled beer (Kronenbourg is just one brand, but Carrefour do a better own-brand one - if I remember correctly, you have Carrefour in Spain?). They work out at about half the syns of an alcoholic one. I can't honestly taste the difference, especially in a shandy.