How drink calculator Works
The consumption formula
The catering standard: 2 drinks per guest in the first hour, 1 drink per guest each hour after — a 25-guest, 4-hour party plans for 100 drinks. The crowd-style multiplier trims or pads that (light crowds drink ~75%, lively ones ~125%). This is hospitality math, not medicine; a glass held all night still counts as one drink, and that's fine.
From drinks to containers
Bars convert: one 750ml bottle of spirits ≈ 16 standard drinks, one wine bottle ≈ 5 glasses, beer counts itself in cans. The calculator splits your total by the crowd's mix and rounds up to buyable units — 7.3 bottles of wine means buy 8, and the leftover becomes next weekend's problem.
The non-alcoholic half
Plan everyone at 2 non-alcoholic drinks in the first two hours — water, soda, sparkling something — plus full coverage for your non-drinking guests across the whole party. Rules of thumb: 1 pound of ice per guest per 2 hours for drinks (more outdoors), and coffee or tea if the party passes hour four. Guests who drink less alcohol drink more of everything else; the calculator builds this in.