A large can (50 cl) of mid-strength beer (3,5% alcohol) contains 4.3 cl spirits (40% alcohol).
You should know approximately how much alcohol is present in common beverages, as it is probably much more than you imagine.
Spirit (40% alcohol) equivalents in beer and wine:
To calculate the amount of 40% alcohol in an alcoholic beverage, you first multiply the alcohol content by the amount and then by 0.025.
Using this method you can, for example, calculate that 50 cl of 3.5% beer contains almost 4.4 cl of spirits (50 x 3.5 x 0.025 = 4.375).