Hi XXXXXX,
There are a few factors to consider. Are you using disposable glasses or real glass? How long is the party? If you're using real glasses will you have someone washing glasses as you go along?
Many opt for the disposable cups, as you don't have to worry about breakage and there's an easy clean up. But nothing shows class like real glass, so some are willing to pay the extra price. 500 plastic glasses for a 4 hour party is a good estimate (or glass without a washer). About 250 glass cups, if you have someone washing.
I hope this helps, if you have any further questions, feel free to ask, it costs nothing to click reply. If this has helped, please remember to click the green accept button.
Warmly,
Chase
Just Answer Wedding Mentor
Wedding Planning, Decorator, Special Event Coordinator, Publicist, General Ettiquette