The difference between forehead temperature and armpit temperature is mainly related to the external environment, and usually the difference between the two temperatures can be up to 1 degree. Because the forehead is exposed to the outdoor environment, it is especially vulnerable to the outdoor environment temperature. If the outdoor environment temperature is high or forehead temperature will be high. If the outdoor ambient temperature is low, the measured body temperature will be low, unlike the armpit temperature which is relatively constant, so the measured body temperature does not truly reflect the human body temperature. Therefore, the forehead temperature should be measured in a relatively small air flow, that is, relatively windless environment to measure the body temperature is relatively accurate. In addition, the body temperature under the armpit should use a thermometer, and body contact for more than 10 minutes to measure the body temperature is relatively accurate, so try to use the body temperature under the armpit to measure relatively more accurate.