Inexpensive Instant-Read Thermometers

From Season 8: More Chicken in a Skillet

Sight, touch, and instinct are age-old ways to gauge when food is done, but for consistent results, none is as reliable as taking the food’s internal temperature. There are many types of specialty thermometers on the market, designed specifically for everything from meat to cappuccino. Yet for home cooks the most useful model is the least specialized of them all, the instant-read thermometer. This device can be inserted into almost any kind of food to display a reading of its internal temperature within seconds. Unlike traditional meat thermometers, these quick-reading units are not designed to be left in the oven. Prolonged exposure of the whole unit to heat will destroy an instant-read thermometer.

After testing, we developed the following criteria for an acceptable thermometer: A broad range to cover high and low temperatures; a stem long enough to reach the interior of large cuts of meat; a way to recalibrate slips in accuracy; and, above all, speed, so you don't have to keep the oven door open too long.

One of the primary design differences among instant-read thermometers was the type of display—dial face or digital. Though pocket-sized dial face thermometers are less expensive than digital models, they are much less legible, and most have narrower effective temperature ranges than the digitals. Both digital and dial thermometers are mechanically capable of covering wide temperature ranges, but dial thermometers cannot offer the same readability over wide ranges because their faces become too compressed graphically to read small changes. As a result, while digital displays show the numbers clearly and display the temperature to the degree (or in some cases, even tenths of a degree), most dial faces are marked with faint lines every two degrees, leaving you squinting and unsure of whether your loaf of bread is at exactly 195 degrees.

Another important difference between digital and dial models is the location of the temperature sensors. On dial face thermometers, the sensors are located roughly one and one-half inches up from the tip of the stem. The sensors on digital thermometers, on the other hand, are located at the very tip of the stem. In our testing, this difference mattered most when measuring the temperature of shallow liquids. Our top digital thermometers could produce an accurate temperature reading in liquids of one inch deep or even less whereas the dial models needed at least one and one-half inches.

On the other hand, some cooks prefer dial face thermometers because many of these models can be recalibrated manually by adjusting a nut at the base of the dial whereas digitals cannot be recalibrated. However, we tested the calibrations of all our units in boiling water, which should read 212 degrees, and in a slurry of ice and water, which should read 32 degrees, at both the beginning and the end of our six-week testing period. All of their calibrations held from beginning to end, which led us to believe that the digitals’ lack of ability to recalibrate is not the disadvantage it might seem at first. Given these factors, we found that we generally preferred digital thermometers over those with dial faces

We noted one difference among digitals that affected cost. Our higher priced models are outfitted with a thermocouple sensor, whereas the less expensive models register temperatures with a thermistor, which is a cheaper circuit that comes with a sacrifice in speed. Our preferred model has the thermocouple sensor, but we found a best buy model with thermistor.

Several models offered high enough temperature ranges to use for deep frying or sugar syrup, however, none really made it as high-quality pinch hitters in this department. Many allowed maximum temperatures just a few degrees above the 375-degree oil that is required for deep frying, easily risking damage to the thermometer. They also lack the clip by which a thermometer could be attached to a pan wall so the stem could remain in the hot oil or sugar syrup. Readout clarity was also a problem.

One note: digitals are electronic and do require batteries. This might be annoying when you reach for a thermometer and find that the battery has died unexpectedly. Because battery life can be extended by shutting the thermometer off when it is not in use, we think it’s essential that digital thermometers have an automatic shutoff, or at least an on/off switch.

Note: The models of the CDN thermometers that we tested have been discontinued. When new models are available to the general public, we will update this review. The Super-Fast Thermapen has also been discontinued. See the related Thermapen Thermometer testing (at right) for our review of the new, upgraded version.