5 Rules for Making Ice Packs Work in a Cooler

Pre-chill everything Ice packs have less thermal mass than ice, so they cannot cool warm items. Put drinks in the fridge overnight and chill the cooler itself in a cool place or with a bag of ice for an hour before packing.

Use as many ice packs as you can fit More ice packs mean more cold retention. Fill every gap — air space is the enemy of insulation.

Pack the cooler tight Leave as little empty space as possible. A full cooler stays cold longer than a half-empty one.

Minimize opening the lid Every time you open the cooler, cold air escapes. Open it only when necessary and close it quickly.

Remember: a cooler only slows warming A cooler does not make things cold — it just insulates. If you start with warm contents, they will warm up faster.