Three to five days in 90°F.

That’s your real-world answer for a high-end roto-molded cooler (Yeti, Pelican, RTIC, etc.) with block ice in 90°F heat. If you use cubes, knock a day off.

Manufacturers claim 7+ days. That’s in ideal conditions — 70°F ambient, pre-chilled cooler, full of block ice, never opened. At 90°F with standard use (opening a few times a day for drinks), you’re looking at 3-5 days. Pre-chilling the cooler and using large block ice (not cubes) gets you closer to the 5-day end. Dry ice or ice packs extend it, but that’s cheating.

The rotomolded construction helps, but insulation only slows heat transfer — it doesn’t stop it. In 90° weather, the delta between inside and outside is big, so your ice melts faster than the marketing suggests.

Plan for three days, be happy with five. If you need a full week, bring backup ice or a second cooler.