The Best Refrigerator/Freezer Thermometers

All of the models had at least two parts: a display that mounts magnetically on the outside of the refrigerator or sits on the counter, and a temperature sensor that goes inside the refrigerator and relays temperatures to the display. One model was wireless, but its temperature sensors were embedded in large cases that hogged valuable space in the refrigerator and freezer. We preferred models whose sensors were attached to wire probes that snaked from the display or monitor to the refrigerator or freezer—the wires were unobtrusive and easy to position anywhere in the refrigerator. (Don’t worry—your refrigerator or freezer will still seal tightly with the wires running inside, as the wires are quite thin.)

We also preferred models that came with two sensors, which allowed us to monitor refrigerator and freezer temperatures simultaneously. All thermometers allowed users to track both the maximum and minimum temperatures measured and to set audio and/or visual alerts to go off when temperatures went above or below customizable points (while alert styles varied, all models continued to indicate that the temperature had gone out of range until the user reset the alarm). In general, we liked models that were intuitive to navigate and program and had large, easy-to-read displays that made it clear when we were looking at current temperatures and when we were looking at maximums or minimums. Some users preferred visual alerts, and some preferred audio. Options differ from model to model; our favorite allows users to choose either or both.

All the models were reasonably accurate when placed in an ice bath and when used in the refrigerator, living up to their manufacturers’ claims to measure temperatures within 2 degrees of those recorded by a lab-grade thermocouple. In the freezer, however, two of the models faltered a bit, recording temperatures that were off from the thermocouple’s readings by an average of 2 to almost 4 degrees; while small fluctuations like these won’t normally be a problem, we preferred models that recorded temperatures that were as close as possible to those registered by the thermocouple.

Our winner, the ThermoWorks Fridge/Freezer Alarm, was the most accurate thermometer in our testing. It had two probes and a clear, though relatively small, display. Its interface was a little tricky to navigate, but an extra feature more than made up for this minor flaw: This unit not only alerts you when temperatures go above or below the temperatures you designate, but when temperatures remain outside those points for more than a half-hour, the thermometer tracks the duration of that infraction, letting you know exactly how long your food has been out of the target zone. Finally, this thermometer is durable: To simulate a year’s use, we installed it in a refrigerator and then opened and closed the door 1,000 times. Afterward, the wire probes were good as new and registered the ice melting point as accurately as they had the first time.