Plan for two days with a good cooler.

Two to three days, assuming you started with enough ice and a quality cooler. Opening it twice a day helps a lot, but it’s not magic.

The real variables are ice-to-contents ratio (more ice means more cold mass) and how well the cooler is insulated. A cheap rotomolded cooler will outperform a flimsy plastic one. Pre-chilling the cooler and food before packing buys you extra hours. Ambient temperature matters too — 90°F sun is way different than 60°F shade.

If you’re packing for a weekend, load up on block ice (melts slower than cubes) and keep the cooler in the shade. Two quick openings per day is about as good as you can manage without a freezer.

Don’t push it past three days without checking internal temp or swapping ice.