Pounds of ice per guest
Ice does three jobs at a party, and each needs its own allowance. In drinks: a highball or rocks glass takes 4–5 oz of ice, and a guest gets through 4–6 drinks in an afternoon, so about 1 lb per person ends up in glasses. In coolers: chilling a case of cans takes about 20 lb, and keeping it cold all day takes more — roughly another ½ lb per guest. Weather: outdoors above 85°F, ice melts twice as fast; add ½ lb per guest on top.
That gives the working numbers: 1 lb per guest for a bar with pre-chilled drinks, 1½ lb per guest for the typical party with coolers (the number our drink calculator uses), and 2 lb per guest for a hot outdoor event or anything over 5 hours.
Ice chart by guest count
| Guests | Drinks only (1 lb) | With coolers (1½ lb) | Hot outdoors (2 lb) | Bags to buy (1½ lb plan) |
| 10 | 10 lb | 15 lb | 20 lb | 2 × 10-lb or 1 × 20-lb |
| 20 | 20 lb | 30 lb | 40 lb | 3 × 10-lb or 2 × 20-lb |
| 30 | 30 lb | 45 lb | 60 lb | 5 × 10-lb or 3 × 20-lb |
| 50 | 50 lb | 75 lb | 100 lb | 8 × 10-lb or 4 × 20-lb |
| 75 | 75 lb | 113 lb | 150 lb | 12 × 10-lb or 6 × 20-lb |
| 100 | 100 lb | 150 lb | 200 lb | 15 × 10-lb or 8 × 20-lb |
| 150 | 150 lb | 225 lb | 300 lb | 23 × 10-lb or 12 × 20-lb |
Bagged ice is sold in 7-, 10-, 16- and 20-lb bags depending on the store; at $2–4 per 10-lb bag, ice for 100 guests is $30–60. Above 200 lb, an ice delivery service is usually cheaper and saves the trunk.
Chilling drinks in coolers
The rule for coolers is two parts ice to one part drinks by volume. A 48-quart cooler holds about a case of 24 cans plus 20 lb of ice; a 70-quart cooler, two cases plus 30 lb. Layer ice–cans–ice, and if the drinks start warm, add water and a cup of salt: the brine pulls cans down to 40°F in 20–30 minutes instead of two hours. Drinks that go in already cold need half the ice and stay cold twice as long. Keep the cooler in the shade with the lid closed, drain a little meltwater periodically (but not all — cold water chills better than air), and use a separate cooler for drinking ice so nobody's scooping from around the beer cans.
Ice for drinks and the bar
Bar ice should be clean bagged ice or ice-machine ice in a lidded tub or insulated ice bucket, never from the drink cooler. A bartender goes through about 1 lb of ice per guest per 4 hours in glasses; add 10 lb for shaking cocktails and 5 lb per punch bowl or dispenser. For wine and champagne in tubs, a galvanized tub holds 12 bottles with about 20 lb of ice and water. Buy crushed or nugget ice for cocktails and tubs if you can find it — it chills faster — and cubes for the coolers, which melt slower.
How long ice lasts
- Closed hard cooler, shade, 75°F: a 20-lb bag lasts 8–12 hours; a premium rotomolded cooler, 2–3 days.
- Open drink tub, indoors: 3–4 hours before it's mostly water.
- Open tub, outdoors, 90°F sun: 1½–2 hours. Refill in the second hour.
- In glasses: gone in 20 minutes, which is why the per-guest number is higher than people expect.
For a 6-hour outdoor party, buy in two trips or ask a guest to bring the second half at the 3-hour mark. Freezer space matters too: a standard home freezer fits 3–4 bags; the rest has to live in coolers from the moment you buy it. Pre-chill the coolers themselves overnight with a sacrificial bag of ice, dump it, and load fresh — that alone extends ice life by a couple of hours.
Two mistakes to avoid
The first is buying it all the day before and letting it fuse into a solid block; if you must buy early, keep the bags flat in the freezer and give them a whack on the driveway before opening. The second is using the same ice for coolers and drinks — people will not drink from the cooler once they've watched a wet hand fish out a beer. Two coolers, two labels, and a scoop on a string.
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Frequently asked questions
How much ice per person?
1 lb for drinks alone, 1½ lb with coolers, 2 lb outdoors in hot weather.
How much ice for 50 people?
About 75 lb — eight 10-lb bags or four 20-lb bags. 100 lb outdoors in summer.
How much ice for 100 people?
150 lb indoors with coolers; 200 lb outdoors. Consider ice delivery.
How much ice for 20 people?
About 30 lb — three 10-lb bags.
How much ice for a wedding of 150?
About 225 lb, or 300 lb for an outdoor summer reception.
How much ice for a cooler of beer?
About 20 lb per case of cans; add water and a cup of salt to chill warm cans fast.