The holiday cooking season is here, and that means your oven is about to get a real workout. If you’ve had trouble getting your baked goods or roasted meats to turn out according to the recipe, it could be that your oven’s accuracy is off.  A good cook should know their oven well. Are the settings accurate? How stable is the oven after it gets to the set temp?

The experts at America’s Test Kitchen say, “Ovens are inaccurate. Since all ovens cycle on and off to maintain temperature, even the best models will periodically deviate from the desired target by at least a few degrees throughout cooking […] On top of this,” they say, “we’ve found that ovens set to the same temperature can vary by as much as 90 degrees.”

If you set the oven to 350°F, but the center of your oven is actually cooking at 330°F, your baked goods will take longer to brown. If the oven temp is higher—say, 370°F—cakes will dome and cookies can brown on the outside while remaining undercooked inside.

The Truth About Your Oven’s Heating Cycle

Ovens have thermostats that trigger a heating cycle to keep the internal temperature near the set temperature. For example, if you set the oven to 350°F, once it gets there, the internal thermostat turns the heat off. Then, when the temperature falls somewhere below the 350°F set point, the heat will switch on again. The actual temperature in the oven will “oscillate” or bounce up and down around your setting over the course of several minutes per cycle. The variance between the high and low peaks can be quite large. At a setting of 350°F, the actual peaks and troughs might be as high as 400°F and as low as 300°F.

Oscillation isn’t the only problem. Some ovens are more accurate than others, and even the most accurate ovens can become less accurate over time. In fact, most ovens are off their set point by about 25-50°F. And if your oven is set to 325°F (163°C), but averaging a higher temperature of 360°F (182°C) at that setting, your cooking results will be off the mark.

This is why it’s important to test your oven’s accuracy.

How to Test Your Oven’s Accuracy

To test your oven’s accuracy, you’ll need an air probe, ChefAlarm^®, and grate clip. You can also use any cloud-enabled thermometer for this task.

1. Start with your oven turned off.
2. Set an oven rack in the oven’s center position and attach an air probe to the middle of the cooking rack using a grate clip.
3. Set the high-temp alarm to 350°F (177°C).
4. Start the count-up mode on your ChefAlarm by tapping the “Timer Start/Stop” button. (This will tell you how long it takes your oven to preheat.)
5. Set the oven to 350°F (177°C) and close the door. Do NOT open the door while the test is running!
6. When your oven finishes preheating, clear the Min/Max on your ChefAlarm. Set your timer for 30 minutes and allow the oven to continue to run.
7. When the timer sounds, note the Max and Min temperatures shown in the upper left-hand corner. This shows you the oven’s oscillation while stabilizing around your target temperature.
   
   
   
8. Clear the Min/Max readings again, and set another 30-minute timer.
9. After the second half-hour, note the second set of Min/Max temperatures. This set will give you a better sense of the performance of your oven during a longer cook.
10. Take the average of the second two numbers to get your oven’s temp. For example, if your second set of temperatures yielded a Max of 378°F (192°C) and a Min of 354°F (179°C), your average oven temperature is actually 366°F (186°C).

The difference between this number and the original setting is your “offset.” In our example, your oven would have a 16°F [9°C] offset—the difference between 366°F (186°C) and 350°F (177°C).

Some ovens can be calibrated to adjust the set-point and/or to minimize the oscillation. Consult your oven manufacturer for instructions to see if your oven has that feature. If so, follow the instructions or call a service technician to put the oven back into calibration.

If, however, your oven is not easily calibrated, use the offset temperature you calculated to manually adjust your oven settings. For example, a 16°F (9°C) offset would mean that if the recipe calls for 350°F (179°C), you should set your oven to 334°F (168°C).

• The same offset should hold true for higher and lower temperatures since the error is in the thermostat. But to be completely sure, you could perform this same calibration test at different set temperatures.
  
  
  

An easier method of oven verification

If you don’t want to do the math and the checking involved with the ChefAlarm method, get a Square DOT®, which has an oven-temp averaging function built in! You set your oven temp, use the included air probe, and it starts taking a running, 15-minute average and displays it right on the face. It’s easy and effective!

Even expensive ovens with microprocessor controls and digital displays will oscillate and need to be checked for accuracy. And you should be aware that even an advanced oven that can be switched between convection and traditional heat will actually perform differently between the two methods. Check your oven in both modes!

For all your holiday (or any other day!) baking and roasting, you depend on your oven’s accuracy to get the results you want. By checking how accurate your oven actually is, you can improve all of your oven-based cookery. Get the perfect browning, the perfect crust, the perfect everything by making sure your oven isn’t ruining things for you. Using ChefAlarm, or any of our other Min/Max-enabled leave-in probe thermometers, will give you the confidence you need to cook successfully during the holidays and throughout the whole year.