Ice calculator: how much ice for a party

The usual rule is 1 to 1½ lb of ice a guest. That is about right when drinks are iced and bottles are kept in the fridge. When beer, wine and soda sit in tubs or coolers of ice, plan on 2 lb a guest or more — the bottles need their own ice, and on a hot day outdoors, more again.

For 50 guests at a four-hour mixed-bar party with drinks kept in ice tubs, the calculator gives about 110 lb, or 22 five-pound bags. On a hot day outdoors that rises to around 150 lb. If the bottles are in the fridge and only glasses need ice, about 45 lb is enough.

Allow about a pound of ice for every bottle or can you want kept cold in a tub or cooler, on top of the ice for glasses. Layer ice under, between and over the bottles, and add cold water once it starts to melt — ice water chills bottles faster than ice alone.

Buy it as late as you reasonably can — the morning of the party, or pick it up on the way home. If you must buy it the day before, keep it in the freezer, or in a closed cooler in the shade, and buy a bag or two extra for melt.

About 6 oz of ice fills a highball or rocks glass. Wine is not iced, and most beer is served from the bottle, so a wine-led party needs much less glass ice than a cocktail party.