A good rule of thumb for estimating is 2-3 drinks per person for the cocktail hour, then 1 drink per person per hour for the rest of the reception. So for example - for a cocktail hour then 4 hour reception for 65 guests you'll need to be prepared to serve at least 350-400 drinks!
Using this rule, if you have 100 guests at your wedding, and you're planning a five-hour celebration, you're looking at 600 drinks total for the night. Keep in mind that this doesn't include champagne for toasts, which is usually added in addition to your other alcoholic beverage options.
So as guide, if you have 100 guests, you will need around 50 bottles of wine (mix of red and white.) Plus around 300 pints/bottles of lager, beer and cider.
For a 4 hour party with 100 guests, you will need approximately 400 drinks: 160 beers, 144 glasses of wine (29 bottles) and enough liqueur for 96 individual cocktails (amounts will depend upon what type of cocktail you serve). If you aren't serving wine, plan on 240 cocktails.
Full bar – Beer, wine and liquor: 100 (guests) x 5 (hours) = 500 drinks. 500 x 0.33 = 170 beers or 7 cases of beer or one ½ barrel sized keg. 500 x 0.33 = 150 glasses of wine, /5 glasses per bottle= 37 bottles of wine. 500 x 0.33 = 150 mixed drinks, /39 servings per 1.75 bottle = four 1.75ml bottles liquor.
Open Bar for 100 GUESTS: 70 bottles of wine. 175 bottles of beer. 15 bottles of liquor (750 ml) 20 bottles of champagne for toast (optional)
Casual gathering or daytime event: People tend to drink less. Expect 1-2 drinks per person per hour. Evening or formal events: The consumption will likely be higher, closer to 2-3 drinks per person per hour.
(So for a six-hour wedding with 100 guests, you'll need roughly 600 drinks.) Alex Tornai, party planner for Binny's Beverage Depot, errs on the side of more drinks per person (and we're here for it): “Two drinks in the first hour and one drink per hour for the duration of the evening,” he says.