Fridge freezer capacity is measured in litres. That doesn’t necessarily mean you should fill it with wine and beer (unless you want to).
100 - 150 litres - Should suit a household of one or two people.
150 - 250 litres - Better for medium sized families.
250+ litres - For big families or plenty of roommates.
Regular outings to the supermarket should mean you require less refrigeration space. So if you shop often, consider a smaller fridge.
#EASYTIP: Don't overfill your fridge – the cool air needs some room to circulate.