To test freezers, our engineers fill each model with boxes of frozen spinach and run them in our test chambers for approximately six weeks to evaluate how well they keep the packages frozen.

The results allow us to judge their thermostat control and temperature uniformity (the ability to maintain the same temperature throughout the freezer cavity). Our engineers also measure usable storage capacity, which doesn’t always match what manufacturers claim.

In addition, we calculate energy efficiency, evaluate noise output, and judge how long a freezer can keep food frozen during a power outage. All this data is folded into an Overall Score for each model and appears in our freezer ratings charts. 

Stand-alone freezers used to be all about utility, with no-frills designs and an open-box interior that made it a challenge to keep foods organized. Those bare-bones freezers are still available—and many of them do well in our freezer ratings—but we're also seeing a lot of improvements to the look and functionality of freezers. Consider these factors before you hit the store:

Location, Location
If you plan to keep the freezer in a living area, consider how noisy it is (and also how it looks). Most manufacturers say that their freezers can operate in a room where the temperature can reach up 110 degrees Fahrenheit, but check product specifications if you plan to put the freezer in an unheated area, such as a garage.

Sizing Things Up
Freezers, whether chest or upright, come in three basic sizes: compact or small (5 to 9 cubic feet), medium (12 to 18 cubic feet), and large (more than 18 cubic feet). Upright freezers have a smaller footprint for the equivalent storage space.

Blackout Recovery
Most manufacturers say that their freezers can keep food adequately frozen for 24 hours with the power off, as long as the freezer remains unopened. But our tests simulating a prolonged power failure showed that some uprights allowed a relatively large increase in temperature after only nine hours.

Consistency
Most of the freezers in our tests maintained a consistent temperature. Manual-defrost uprights were the exception. Without fans to circulate cold air, temperatures of on-door shelves were between 9 and 19 degrees higher than in the rest of the freezer. 

Energy Use
Don't expect your new freezer to be quite as energy efficient as its yellow EnergyGuide label implies. That's because our tests are tougher and, we believe, more like real-world conditions than those specified by the U.S. Department of Energy. Energy Star products must meet certain governmental energy-efficiency standards.

Once you've gotten your freezer, you may want to give it a little help keeping its cool—and making food last longer. Check out these simple tips from our experts:

Save Energy
Keep your freezer in a cool spot, such as the basement, where it tends to stay well below normal room temperatures. Even though most manufacturers say models will operate in temperatures up to 110 degrees Fahrenheit, check the product info for specifications.

Minimize Frost
Open the lid or door less often. Keep an inventory of what’s inside so you don’t have to hunt around. Label food well for the same reason.

Store Food Correctly
Repackaging food in several layers of plastic wrap helps reduce moisture loss and freezer burn. Some common freezing rules of thumb: You can freeze ground beef for up to 4 months, and a whole chicken for as much as a year. A pack of hot dogs should only stay frozen for 1 to 2 months.