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Nov 6, 2011 09:02 AM


I have two fairly expensive digital instant-read thermometers and one that reads the temperature on a dial.

When the thermometers are inserted in the same area of a beef tenderloin , they all read differently - sometimes as much as 25 Farenheit degrees.

I do not normally use more than one thermometer (honest!) but I was curious one day and decided to compare readings.

This has made me very hesitant to rely on my thermometers and have gone back to using the finger touch to guage the cooking stage.

However, can anyone tell me if this is normal?

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  1. These thermometers are not meant to be extremely accurate anyway. I am not surprise if a thermometer is off by 25 Fahrenheit to be honest. You can always buy a more accurate thermometer, but that will cost more.

    If you are interested, here is an easy test for you to play around. First, see if they both read the same at room temperature, assuming it can read room temperature. If not, something is wrong. Then, boil a pot of water and measure the water boiling point (while it is still boiling). Unless you live at very high attitude, water should boils around 100 degree Celsius or 212 degree Fahrenheit.

    There are all sort of other want to gauge your thermometers but those will require more special materials or tools.

    1. The only thing I have add is that not all thermometers work the same way. Some require only a shallow probe insertion, others require that the probe be inserted to a specific depth (usually indicated by a dimple or other physical feature on the side of the probe). If you're using hour thermometer in strict compliance with the manufacturer's instructions and still find them to be unreliable, then I'd suggest investing in a certified accurate model and throw the unreliable devices in the trash.

      1. Ok this is going to sound funny but to test mine, I could do the water thing but that means all that boiling and so on and it is the usual way to check out a thermometer. But what I do is really quick and easy... I just take my own temperature with it. Pop it in my mouth and hold it under my tongue. I know what body temperature is supposed to be (98.7F) and is really consistent. You can do this quickly with both thermometers, see if the two are comparable, and go from there. I'd keep only one that I was most comfortable with and was most accurate. Then I'd just notice the internal temperature of the next beef tenderloin as per that thermometer vs the doneness of the tenderloin. This will give you the relative temperature reading to note in the future. So if you see that medium done is reading at X degrees, that's what you cook to.
        Thermometers are really variable with respect to their accuracy and unfortunately price isn't necessarily a guarantee of accuracy.

        4 Replies
        1. re: freia

          I am getting a couple of thermapens for family this Christmas. Cooks Illustrated rates them highest. Anyone in chow land have hands-on experience with them? Thanks in advance.

          1. re: dcrb

            cdrb.. I have had mine for several years.... many people ask to borrow it on the job or calibrate their dial analog thermometer with my Thermapen.. I have had mine dropped in a bbq pit and dipped in an ice bath.. with the ice bath I took it apart and dried it out... to sumarize they are accurate, reliable, and tough even if abused.

            1. re: bbqJohn

              I bought a Thermapen a year or so back and couldn't be happier. Every now and then, I will put it in a pot of boiling water just to make sure it still reads right and its always been 210-212F. That's good enough for me.

              1. re: BigE


                I found out they will deliver to Canada so i am all set.
                Have a nice day

        2. Hi, missclawdry:

          The tests that other posters have suggested might work, then again they might not. One thing to consider is from where, *on the probe*, the thermometer is getting its reading. Some are designed and made so that they register from the tip, others register what amounts to the average temperature along the probe. If your two instant-read thermometers are different in this regard, they may pass the "room" and "boiling" tests and still not be the same *in* foods. If this is the explanation, they can be off by your 25F, and this would indeed be normal, if perplexing.

          IMO, the ones that read from the tip are the ones to have.


          3 Replies
          1. re: kaleokahu

            kaleokahu - good morning (at least it is here)

            Thank you so much for your reply - one question though - how do I tell where the reading is obtained? (Hope that question isn't too stupid).

            1. re: missclawdy

              Hi, missclawdy:

              Not a stupid question at all. I'm not sure how to answer you definitively. I would start by asking the *manufacturers* (not the retailer). As another poster here has said, some probes have a dot or crenellation, but I wouldn't necessarily take that as Gospel, either.

              I know that Thermapen has a reduced-diameter tippy-tip, which looks to me to be the business end (the rest, in a much wider diameter, appears to be insulated/isolated against "averaging").

              Finally, I think you may find this link informative if you want to read up:


              Have Fun.



              1. re: kaleokahu

                I have contacted Thermoworks and they do ship to Canada and quite reasonably

                I have also made a request to follow you - I enjoy the way you write

                Thank you again for taking the time to help

                Miss C.

          2. I stick with the dial ones that can be calibrated. Set them to 212 in boiling water and 32 in a glass of a crushed ice/ water mush.


            4 Replies
            1. re: knifesavers


              Do you have a particular brand that you like and use? Thanks.

              1. re: knifesavers

                Do you have a particular brand that you use and recommend? Thanks.

                1. re: dcrb

                  I have CDNs from a long time ago. Today I would get this one.