We selected seven products, priced from $19.99 to $379.99, from five top-selling cooler manufacturers, including a Yeti and a comparable model from Pelican. We chose a mix of models with wheels and without and opted for those with capacities of about 50 quarts—a size that we think should be sufficient for a weekend’s worth of supplies for four people.

We ran the coolers through a battery of tests. To gauge cold retention, we loaded each with 32 pounds of ice and monitored how long the ice lasted. We also filled the coolers with ice packs and soda cans and used thermometers to track how long they kept sodas under 50 degrees. We tested ease of use by attempting to stuff a weekend’s worth of groceries into each cooler, and we carried or wheeled the full coolers across concrete, asphalt, gravel, and grass; up and down stairs; and in and out of the back of a car. Finally, we put the products through abuse tests: We pushed full coolers out of the back of an SUV five times and operated all handles, latches, and hinges a minimum of 100 times.

Functionality issues came up first. One cooler’s lid wouldn’t stay open and repeatedly flopped onto our hands as we loaded it. Another cooler lacked a drain, so we had to unload everything and strain the ice to get rid of excess water. And the high-end coolers were just plain heavy. While every other product weighed between 7 and 12 pounds when empty, the Yeti weighed in at 26 pounds empty and required two people to carry it when full. The Pelican was even heavier, at 38 pounds, and though its wheels helped, lugging it up and down stairs or in and out of the car was still a two-person job.

All that heft, however, made these two coolers less likely to tumble over and more durable when they did. Thanks to sturdier locking latches, the lids on these models never opened when we pushed them out of the SUV. The lighter coolers all spilled open, sending sodas and ice packs everywhere. By the end of testing, one had lost a side handle and another had a dented pole that prevented the telescoping handle from collapsing. The Yeti and Pelican models emerged with only scratches.

Our two high-end coolers also stood out for their superior cold retention. Most of the coolers allowed sodas and ice packs to reach 50 degrees in two days and ice to melt completely in four days. Soda in the Yeti and the Pelican was still 49 degrees after four days; ice melted fully after 10 and eight days, respectively.

Of course, warm soda isn’t the end of the world, but foods such as hamburger and fish are considered unsafe after spending more than 2 hours at 41 degrees or higher, according to the United States Department of Agriculture. With enough coolant and careful packing, all the coolers in our lineup can safely store your food for a day or two, but the Yeti and the Pelican can do so for longer.

To figure out what set these two coolers apart, we had to get inside them. So we bought an electric saw, strapped on safety goggles, and ripped our way through every model in the lineup.

Coolers are made of a hard plastic shell surrounding a thick layer of foam insulation. The specific type of insulation didn’t matter, but the location and thickness of it did. The top four coolers had insulated lids; the rest were just hollow plastic. Because air doesn’t conduct heat well, the hollow models can insulate to a degree, but we found that coolers with added insulation in the lid performed better.

The highly ranked coolers also had thicker insulation all around (though that thickness varied in different parts of each cooler). The coolers that got warmer faster had ½ to 1 inch of insulation. The Yeti’s insulation was double that, ranging from 1.4 to 2.3 inches thick, and the Pelican went even further, with a whopping 3 inches of insulation throughout. But if the Pelican had the thickest insulation, why did the Yeti perform better in our cold-retention tests?

We excavated insulation from each cooler and used a tape measure and a scale to calculate the density. We found that the Yeti’s insulation was less dense than the Pelican’s (35 milligrams per cubic centimeter versus 40 milligrams per cubic centimeter). Though it seems counterintuitive, our science editor confirmed that less-dense insulation can insulate better. Air is a poor conductor of heat, especially when it’s immobile, so it’s the air inside foam insulation that really insulates. The pockets in foam trap air, preventing it from moving, thus creating a barrier between the contents of the cooler and the heat outside. If the insulating material is less dense, it contains more air.

When it comes to cold retention and durability, the Yeti Tundra 50 ($379.99) lived up to the hype—we’ve named it our overall winner. We particularly liked its rubber latches and rope handles, which are durable and comfortable to operate; plus, they’re replaceable if they do happen to break (the company sells these parts on its website). However, this rugged and pricey cooler isn’t for everyone. For more casual cooling needs—a day at the beach or a barbecue—we recommend the Coleman 50 QT Xtreme Wheeled Cooler ($45.99). This budget-friendly model has excellent cold-retention abilities, a roomy interior, and wheels that make it easy to transport.