Working out quantities
How much ice, beer, wine, and liquor to plan for an open bar at 100 guests, with the per-person math caterers actually need for a corporate or private event.
Food quantities get careful attention on most quotes. Beverages, especially for a hosted or open bar, often get a rough estimate tacked on at the end. That is exactly backwards, since running out of ice or liquor mid-event is one of the most visible failures a guest will notice.
Ice melts, so plan it by the hour rather than by the head alone. A workable starting point is half a pound of ice per guest to fill the glasses and the tubs, plus an eighth of a pound per guest for every hour the event runs: a pound a guest at a four-hour reception, a pound and a half at eight. If the same ice is also keeping food cold, start from a pound and a quarter a guest instead. On a hot outdoor event, push higher, because ice for cooling disappears faster than ice going into glasses.
Ice, cups and the containers it all goes in are exactly the things that get left behind on an off-site job. The disposables checklist for off-site jobs has the beverage side as its own section.
Start from the drinks count, about one drink a guest an hour, then split it by who is drinking, which moves it more than the kind of event does. For a wedding of mixed ages, 50 percent wine, 30 beer and 20 spirits; a corporate or daytime crowd runs 55, 35 and 10; a younger, late crowd 35, 35 and 30. Within the wine, about 60 percent white and rosé to 40 red in summer, flipped in winter. Those are the calculator's defaults, and every one of them is yours to change.
A 750 ml bottle holds 25.36 fluid ounces, and drinks per bottle is the whole number of pours in it: at a 5 ounce pour a bottle of wine gives 5 glasses, and at 1.5 ounces a bottle of spirits gives 16 drinks, the one or so left over covering spillage and a heavy hand, or 20 at 1.25 ounces. Beer is one bottle or can a drink, in cases of 24; plenty of venues ban kegs, so plan in cases. Order wine and beer by the whole case and spirits by the bottle across the five a full bar stocks, vodka, gin, whiskey, rum and tequila, rounding each spirit up on its own.
140 guests for five hours is 700 drinks. Wine is 350 glasses, 70 bottles, so 6 cases of 12 with 2 to spare. Beer is 210, 9 cases of 24. Spirits are 140 drinks, 9 bottles in all, but 2 each of five spirits, so 10 on the list.
A champagne toast sits on top of the bar, never inside it: a bottle covers about 8 guests at a half flute, 6 at a full pour. For 140 guests at a half flute that is 18 bottles, 2 cases. Plenty of couples now skip it or toast with what is already in the glass, so ask before you count it.
Mixers run out faster than the liquor they're paired with, especially soda and tonic. Plan mixer quantities against pour count rather than bottle count of liquor. A single bottle of vodka supports far more mixed drinks than a bottle of a sipping whiskey does.
Catering Calc plans 2 liters of mixer for every bottle of spirits the drinks pour, matched to the spirit: soda, tonic and cranberry with vodka, tonic and soda with gin, ginger ale and cola with whiskey, cola and pineapple with rum, and lime juice or margarita mix with tequila. For garnish at a bar of up to four hours, one lime for every five guests at the bar and one lemon for every ten. Both go on the bar list, and in Pro both are defaults you can change.
How many bartenders this volume needs is in the staffing ratio cheat sheet, under bar staff, and if the bar runs alongside passed hors d'oeuvres, how many appetizers per person covers how the food side scales with event length.
These ratios all move together once you know guest count and bar style. Catering Calc's free calculator turns them into bottles, packs and bags of ice from the guest count, the hours and the crowd. Catering Calc Pro turns the same drinks count into a bar order by the case and the bottle, white against red and each spirit rounded up, with no prices on it, so the same list works whether you buy the alcohol or your client does.
Beverage is one of four quantities on the job; the complete catering quantities picture shows how it sits beside food, staffing and disposables.
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