Question: 1g of alcohol is how many ml?
Answer: Alcohol density d=0.8g/ml. Thus: a wine at 12.5 % vol contains 12.5ml of alcohol/100ml of wine x 0.8 g/ml = 10g of alcohol/100 ml of wine. This is the equivalent of 1 drinking unit (= 10 g). This way it is easy to assess the number of units you are consuming.