The Tests

  • Check accuracy in ovens set to 250, 350, and 450 degrees Fahrenheit

  • Evaluate ease of positioning

  • Assess how hard/easy to knock off rack

  • Check readability with oven door open and closed

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.

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, but we’ve also noticed new models on the market and wondered if anything better had come along. We scooped up nine dial-face models priced from $4.63 to $20.94 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.

Does 25 Degrees Off Really Matter?

A number of the products in our lineup have a logo on their packaging and/or the thermometer itself showing that they have been tested by the independent certification organization NSF International and meet standard requirements. The problem is, those standards allow a thermometer to be off by as much as 25 degrees—just the variance we found in some of our brands. To see the impact of such a discrepancy, we baked popovers in ovens that we set to 25 degrees above and below the desired initial temperature of 450 degrees. The popovers in the too-cold oven didn’t rise properly, while those in the too-hot oven were misshapen and overly dark.

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.

Put Your Thermometer Where the Food Is

Many cooks let their oven thermometer live in the oven in an out-of-the-way place where they can check it every time they cook. Not only is that unnecessary (with typical home use, an oven’s temperature should remain relatively consistent over time), it’s also not that helpful. A better approach: First and foremost, place your thermometer in the middle of the center rack, where most food cooks. Set the oven to 350 degrees. A few minutes after the oven has preheated, check the thermometer’s reading. (But don’t wait too long—ovens cycle off and on to maintain a stable temperature.) Remove the thermometer, and make adjustments the next time you cook. Repeat every 3 to 6 months to check that nothing has changed.

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, one earned the top marks. The CDN Pro Accurate Oven Thermometer ($8.70) 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.

Winning Traits

  • Perfect accuracy

  • Easy to position

  • Good stability

  • Easy to read with oven door open or closed