Small inaccuracies in measuring temperature and weight can lead to problems like overcooked roasts and cookies that spread too much, so it’s important to routinely test scales and thermometers to make sure that they are accurate. Here’s how to do it.
If your scale measures in both grams and ounces, testing in grams will provide a more accurate assessment. One nickel should weigh 5 grams. If you are testing in ounces, 4 quarters and 1 nickel should weigh 1 ounce. If your scale is off and cannot be calibrated (check the manufacturer’s instructions), write the discrepancy on a piece of masking tape and affix it to the scale so you can take it into account when you weigh.
A thermometer can be tested in boiling water, which should register 212 degrees at sea level, or in a glass of ice filled with just enough water to reach the top of the ice, which should register 32 degrees. For the most definitive results, test both ways. As with your scale, either calibrate according to the manufacturer’s instructions or make a note of any discrepancy.