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Accuracy of Digital Thermometers?

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In advance of the holiday cooking, I am checking the accuracy of my digital thermometers. Sitting in a jar of warm water, three thermometers show three different temperatures -- a full 10 point difference. Ten points means a lot, to say the least, when roasting meats. Any similar experiences? Any advice?

The three thermometers all are relatively new, used frequently, and name brands.

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  1. Boil some water and check what temperature the thermometer reads. Do it a few times to ensure the thermometer is consistent, and then just adjust. If it was me, I'd actually return any that didn't have water boiling at 100 (Celsius, I don't know Fahrenheit)

    1. The only digital thermometer I have ever owned was a gift purchased from Williams-Sonoma. I made a roast chicken with it which turned out overcooked. I never overcook a roast chicken without a thermometer. I looked up the thermometer on their site and the reviews for it were terrible and had similar overcooked item stories. The gift giver had included a gift receipt so I exchanged it for a nice set of nesting bowls and various other gadgets. I've never felt the need to buy another one after that experience... I seem to do fine without one.

      1. The most reliable way to check a digital thermometer is the ice water test.

        "Ice Water Method - Fill a large glass with finely crushed ice. Add clean water to the top of the ice and stir well. Immerse the thermometer stem a minimum of 2 inches into the mixture. The thermometer should read 32 degrees F after 30 seconds. "
         

        1 Reply
        1. re: C. Hamster

          And you should be able to calibrate your thermometer in ice water .. Check the manual

        2. There are several issues:
          - precision (how fine of differences can it detect)
          - response time (how long it takes to settle to the new temperature)
          smaller tip thermometers are supposed to have a quicker response
          - calibration. Better thermometers meant for food service use can be calibrated, adjusted to match ice water and boiling water temperature.

          I suspect there were 2 issues with your 3 - different response times, and being off on calibration. And when you compare temperatures, make sure the water (or what ever) has a uniform temperature (or is well mixed). There can be different temperatures in a pot of water depending on how close the sides you measure, and how close to the bottom or surface.