Use a basal body thermometer
Take your temperature first thing in the morning
Take it before getting out of bed
Take it before talking, eating, drinking, or moving around
Take it at the same time every day
Use the same thermometer each day
Place the thermometer in your mouth, rectum, or vagina as directed
Keep the thermometer in place until it finishes reading
Record the temperature immediately
Track the temperature daily on a chart or app
Note any factors that may affect the reading, such as poor sleep, illness, alcohol, or travel