How Many Plates, Cups & Napkins Do I Need for a Party?
There is no useful universal answer without knowing how guests will eat and drink. Calculate each item from the number of times it is likely to be used.
Plates
A single plated meal may need roughly one main plate per guest, while buffet food plus cake or dessert can require separate plates. Reusable crockery changes the buying question again.
Cups and glasses
If guests keep one identifiable reusable cup, demand can be close to one each plus reserve. Disposable cups used for multiple drink types or repeatedly replaced require more. Model the behaviour you expect.
Napkins
Finger food, sauces and children's parties can use more napkins than a neat seated meal. Treat napkins as their own quantity rather than copying the plate multiplier.
Contingency
Add a deliberate reserve for dropped or damaged items if useful. Keeping it visible makes it easier to distinguish genuine expected use from “just in case” stock.
Use the Party Supplies Calculator and change each assumption independently.