General Rule of Thumb. A common recommendation is one bartender for every 50-75 guests. For a 120 person wedding reception, this translates to about 2 to 3 bartenders.
We've done smaller weddings with packed bar lines, and larger weddings with lowkey bar lines. It really all depends on your guests! The general rule of thumb is 50 guests for every 1 bartender for a full service bar. If you're just doing beer and wine, you can probably get away with 1 bartender for every 75 guests.
Our catering company's rule of thumb was 1 per every 75 guests. We had 2 with 150 heavy drinking guests and worked out great, no lines! I will say they pre-batched our signature drinks so that kept the lines from forming.
Some of your guests may be light drinkers while others may be heavy drinkers. And then there are always those wedding crashers who show up uninvited and try to drink your bar dry. Assuming that each of your guests will drink two drinks per hour, you'll need one bartender for every 50 guests.
(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.
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.
We'd recommend two to four bars, depending on your guest count (for every 80 to 100 guests, have a bar with two bartenders)—and if you don't have room for that in your venue, try "extending" the bar you do have so you can fit more bartenders to tend to your guests.
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.
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.
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!