Some digital BBT thermometers also store the temperature for you. However, you should still record the temperature in a more permanent way, such as in a BBT journal or in a BBT app on your smartphone. You can also use a non-digital BBT thermometer as long as the thermometer is made to measure your basal body temperature, such as a glass thermometer.

If you are using a glass thermometer, make sure you shake it down at night before you place it on your bedside table. This way, it will be ready to use when you wake up.

Always make sure you get at least three to five hours of continuous sleep before you take your basal body temperature to ensure the reading is accurate. [4] X Trustworthy Source Mayo Clinic Educational website from one of the world’s leading hospitals Go to source

Some women take their basal body temperatures vaginally or rectally, especially if they find it difficult to get an accurate reading using the oral option. Make sure that no matter which method you chose, you stay with the same method for the duration of your cycle. Always place the thermometer in the same spot and at the same depth vaginally and rectally.

Make sure the chart includes a vertical section for the day of your cycle (1,2,3, etc), the month, and the date. It should have an horizontal section with a temperature range of 99°F to 96°F. Before ovulation, a woman’s BBT averages between 97°F (36. 1°C) and 97. 5°F (36. 4°C). After ovulation, it usually rises 97. 6°F (36. 4°C) to 98. 6°F (37°C). You can view a sample BBT chart online. [6] X Research source

Notice if there is a temperature shift of at least 0. 4 degrees within 48-hours on your chart. This is a sign that you are ovulating. The temperature shift should be higher than the highest temperatures that you recorded the previous six days. Most women have a basal body temperature of 96 to 98°F (35. 6 to 36. 7°C) one to two days before ovulation. [8] X Research source

If your basal body temperature stays up for more than 18 days after you have ovulated, you should get tested for pregnancy. [9] X Research source