BBT stands for “basal body temperature”. Your basal body temperature is the temperature of your body taken immediately after you wake up, first thing in the morning.

The thermometer used for this is different than your typical thermometer. Because the changes in temperature can be slight, the thermometer has to be highly accurate, usually displaying your temperature to 1/100 of a degree (e.g., “96.42 degrees” compared to “96.4 degrees”).

Your body’s basal temperature changes in a regular pattern throughout your cycle, because of hormone changes in your body. Tracking your temperature allows you to know where you are in your cycle. You are essentially using body heat to track your reproductive hormones. Knowing exactly where you are in your cycle can give you valuable information about when you will have the best chances to conceive.