How to calibrate your oven, without a thermometer.

New Year. New oven.

Which means that I need to learn the quirks of this new oven.

And of course the first time I baked some chocolate chip cookies for my man, they took 45 minutes, instead of 15 and were still not fully baked…

My first impulse is to blame myself, check the recipe and try again. And Again, the same results.Now this is a pretty high tech oven and you can calibrate the oven up to 35˚F either higher or lower than the stated temperature. But first, you need to know what the actual temperature is.

You can do this one of two ways: Firstly, You buy an oven thermometer and set, and then reset the temperature when the oven comes to temp, my problem here is that how do you know if the thermometer you bought is calibrated? More calibration needed. Also you are always resetting the oven after it comes to temp.

And secondly, you can use an item that undergoes a phase transition at a specific temperature, meet sugar. Sugar melts at 366˚F. Although at exactly 366˚F it maintains its structure and completely melts at 367˚F.


So here’s what you do.

  1. Set your oven to 350˚F and place half a tablespoon of table sugar on a baking sheet (line your sheet with parchment or a silicone mat to help with clean up). Place in oven for 15 minute.
  2. If the sugar melts, lower the temperature by 10˚F (wait for the oven to come to temp) and repeat the experiment.
  3. If the sugar does not melt, increase the heat by 10˚F and repeat the experiment.
  4. Keep repeating the experiment until the sugar melts completely in the 15-minute bake time.
  5. This will be your new bake temp.

Now there is a simple bit of math to do.

I shall use my results here:

Melt temperature of sugar 366˚F

Set temperature when sugar melted: 380˚F


Your equation is: TMelt-TSugar= Melting Temperature

Where TMelt is the temperature at which your sugar melted, in my case 380˚F (this may be lower or higher, bear with me).

And TSugar is 366˚F

Now if you plug the equation: 380-366=14

This means that my oven runs 14˚F COOL, and you need to INCREASE the temperature when you set it.

I can now electronically calibrate my oven.

If you have an oven that is not as crazy high tech as mine, you can put a note on your oven reminding yourself to add 14˚ F every time you set the oven. Or just remember the difference.


Now let’s try the same problem with a lower temp. For instance, the temperature was 335˚F when the sugar melted.

TMelt-TSugar= Melting Temperature

335-366= -31

Your oven runs HOT. All this means is that you will set your oven 31˚F LOWER than the recipe calls for when you bake.

In short, after plugging the equation, and you get a positive number; you need to raise the temperature by that number. If you get a negative number, you need to lower the temperature by that number.

This experiment may take some time, so set aside the better part of a morning to do this. But if you’re like me and your kitchen is your happy place, this should be no problem.

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