The Great Can Cooler Test

Key Takeaways

Double-Walled Insulation Works

Most of our koozies are made of foam – either hard foam that holds its shape, like the Grip-It Can Cooler, or soft and flexible neoprene, which is the same material wetsuits are made of. These work by insulating your drink from the heat in your hand, while also wicking away the condensation.

However, our two standout koozies were both double-walled vacuum-insulated steel. These only do the insulating part, not the wicking part, but they do it so well that it’s enough. The outside of these koozies is steel, then there’s a gap, then there’s another steel wall, and then that’s where your drink goes. Between the walls is a vacuum, which means there’s no air. No air means the heat from outside the koozie can’t travel through this gap, so it can’t reach your can and heat up the liquid inside.

We also had a metal koozie with a thin foam lining, which wasn’t double-walled. This was the third most effective of the 12oz can koozies (i.e. of all the koozies this size, it had the third-lowest average increase after 30 minutes and 3 hours.) But it performed like a really good foam koozie, nowhere near the same as the double-walled koozies.

The Foam Koozies Varied in Effectiveness

The results from the bottle koozies were within just a few percentage points of each other, and ditto for the glass koozies. You might think it’s because they were all foam koozies, so you’d expect them to perform similarly. However, the foam koozies on the 12oz soda cans and 12oz energy drinks showed a wider range of change.

Excluding the metal koozies, for the 12oz soda cans, the difference between the lowest and highest average temperature increase after three hours was 14.8%. In other words, the 12oz soda can foam koozie with the lowest average change increased 14.8% less than the one with the highest average change. That’s quite a lot! For the energy drinks, it was 8.6%. So some koozies really are more effective than others, even when they’re made from very similar material.

Most of the Total Change Had Already Happened by 30 Minutes

If you’re thinking that three hours seems like a really long time to leave a drink unrefrigerated, you’re right, it’s straight-up uncouth. While you probably wouldn’t do that (not twice, anyway), leaving a drink out for 30 minutes seems way more likely. But even after just 30 minutes, all the drinks had already gained more than half of their final percentage increase.

Take the FoamZone Collapsible Can Cooler, which came middle-of-the-pack for our average temperature increase metrics. This drink’s temperature increased by an average of 48.4% over three hours. However, after 30 minutes, it had already increased by an average of 34.4% – which means that 71% of its temperature gain happened in the first 30 minutes.

That’s still better than the koozie-less 12oz can, which increased by an average of 50% after 30 minutes and 66.3% after three hours. So your best bet for enjoying a cold beverage on a warm day is to use a koozie and drink quickly!