Where is the most accurate place to check body temperature?

The most accurate way to measure your body temperature is by taking a rectal temperature. This is because rectal temperature most closely reflects your body's core temperature. Other methods of measuring temperature, such as oral, axillary (armpit), or tympanic (ear), can be less accurate and are more prone to error. For the most accurate reading, it's recommended that you use a digital rectal thermometer and insert it about 1 inch into your rectum.