Oven Thermometers

How We Tested

For reliable, consistent results with recipes, a good oven thermometer is critical. When we used a high-tech digital thermometer to take the temperature of five different home ovens preheated to 350 degrees, some missed the mark by as much as 50 degrees. Here’s one big reason why: An oven’s internal thermometer only gauges the temperature of the location where it’s installed, which is necessarily in an out-of-the-way spot in the back, front, or side of the oven box. But these areas can be subject to hot spots or drafts that make their temperatures differ from the center of the oven. Only a good freestanding oven thermometer can tell you what’s really going on right in the middle of the oven, where most food cooks.

For several years, we’ve relied on our winning dial-face oven thermometer from Cooper-Atkins, but we’ve also noticed new models on the market and wondered if anything better had come along. Would we find the new best oven thermometer? We scooped up nine dial-face models, all priced less than $20, to pit against it. (We avoided bulb models since we’ve found that their tinted alcohol can get stuck and give inaccurate readings.) Most of our lineup had the option to hang from the racks or sit upright. Either way, we wanted a thermometer that was easy to position and remove for a periodic reading. In addition to ease of use, we rated the legibility of the faces and, most importantly, the models’ accuracy. Finally, to assess quality control, we purchased four copies of each thermometer and ran the entire set through testing.

Temperature Trackers

An unreliable oven thermometer is worse than none at all, so we started by evaluating each brand’s accuracy at 250, 350, and 450 degrees, using the same oven for all of our tests. We clipped a lab-grade thermocouple to the center of the middle oven rack and arranged all four copies of a model closely around the probe. We then compared their readings to the thermocouple’s.

All dial-face thermometers work by the same internal mechanism. A bimetallic strip (that is, two pieces of different metals pressed together) is wound into a tight coil and connected to a tiny dial. The two metals expand and contract at different rates when heated or cooled, moving the dial on the face. As simple a mechanism as this is, quality controls clearly vary from factory to factory. With three products, one out of the four copies faltered, registering temperatures 10 to 25 degrees off the real oven temperature.

Easy Reading

Most of the models in our lineup had thin, flat bases designed to sit atop the oven racks. Models with bases less than 2¼ inches wide were difficult to position and prone to tipping over. We found similar fault with two models with clamp-like bases designed to clip onto the grates. The space between the open jaws of the clamp was too narrow to slide over the racks in all five of the different oven styles we tested. At best, they slid on crooked and were difficult to read. At worst, they fell off completely and landed on the oven floor. After one such tumble, the silicone backing on one model melted and warped. The glass face of another top-heavy model cracked when it hit the oven floor.

Finally, we focused our attention on how easy it was to read each model with the oven door open and closed. Our testers favored models that had minimal markings beyond 50- and 25-degree indications, since having more tick marks made them harder to read, and the extra marks were unnecessary anyway. We also knocked off points on models with metal casings that obscured the numbers or cast long shadows on them, forcing us to crouch or squint to read the temperature.

In the end, nearly half our lineup failed to meet our basic criteria for legibility and stability. Add to that the three models that faltered in our accuracy tests, and we were left with just four oven thermometers that met our expectations. Of these, our winner earned the top marks. It has large temperature markings and a simple, streamlined face—plus, a wide base that fits securely on all types of oven racks without fiddling or fussing. It’s our new winner, and one that we’ll be keeping within easy reach to check our own ovens.

Methodology

We tested 10 dialface thermometers, priced from about $5.00 to $20.00, all with a temperature range of at least 150 to 500 degrees Fahrenheit. Prices shown were paid online. Models appear in order of preference.

• ACCURACY: We weighed this criterion most heavily in our rankings. We tested four units of each model in ovens set to 250, 350, and 450 degrees Fahrenheit, using a lab-grade thermocouple to assess their accuracy. Models lost points if one unit was off by more than 10 degrees.
• EASE OF USE: We rated each model on how easy it was to position and remove and on its stability on the rack. Thermometers lost points if they tipped over, fell off the rack, or were difficult to install.
• LEGIBILITY: We evaluated how easy it was to see the thermometers’ temperature readings with the oven door open and closed. Models with sharp color contrast and clear temperature indications fared best.