Now this is always a hard question but there are some rules of thumb that can help.
Firstly (and quite obviously), you need to know your customers. If you know your customers, this makes answering this question so much easier.
There is a simple, rule of thumb ratio that we can use to make sure you have enough glasses to go around and it goes like this.
You need to know the capacity of your pub, club or event. So as an example let's use 100 as your capacity.
You must try and split up your types of glasses too, to primary, secondary and tertiary.
So in our example, a pint glass is our most common glass and with the 3:2:1 rule, it means we must have;
The rule allows us to have some extra glasses in the back too for cleaning.