About this tool
The Party Ice Calculator is a free, in-browser tool that tells you how many pounds — and how many bags — of ice to buy for an event, covering both the ice that goes in drinks and the ice used to chill bottles, cans, and coolers. Enter your guest count, event length, the weather, and how much you're chilling down, and it returns the total pounds and the bag count for your chosen bag size. Everything runs locally in your browser and nothing you enter is uploaded.
The method starts from a base of 1 lb of drinking ice per guest, then scales it two ways. An hour factor stretches supply for longer events: 1 + 0.25 × (hours − 2), so a 4-hour party uses 1.5× the base and a 2-hour party uses 1×. A weather factor accounts for melt and heavier drinking — cool 1.0, warm 1.3, and hot (above about 85 °F) 1.6. On top of that, chilling adds ice directly: about 1 lb for every 2 drinks you're icing down, plus 10 lb per standard cooler. Total = ceil(guests × hour factor × weather factor + chilling add), and bags = ceil(total ÷ bag size), with 20, 10, or 7 lb bags available.
As a worked example, 40 guests at a warm 4-hour party need 40 × 1.5 × 1.3 = 78 lb of drinking ice; add a cooler (10 lb) and you're at 88 lb, or five 20 lb bags. A useful sanity check is 1.5–2 lb of ice per guest for a typical warm three-hour party. Ice melts faster than people expect, especially outdoors, so buy on the generous side and keep spare bags in a shaded cooler.