How to Take your Basal Body Temperature

Materials needed

Basal body thermometer


  1. Shake down the thermometer to below 95°F and place it by your bed before going to sleep at night.
  2. Upon waking, place the thermometer in your armpit for a full 10 minutes. It is important to move as little as possible; lying and resting with your eyes closed is best. Do not get up until the 10 minutes have passed.
  3. Record the temperature for a least 3 to 5 mornings (preferably at the same time of day). Menstruating women must perform the test on the second, third, and fourth days of menstruation. Men and postmenopausal women can perform the test at any time.

Under ideal conditions, the basal body temperature gives an indication of what is occurring during optimal thyroid output. Further, it gives a good indication of what is occurring at the cellular level by measuring the body’s metabolic response.

What do your numbers mean?

A temperature between 97.6 and 98.0 °F denotes a normally functioning thyroid. A temperature lower than 97.6 °F may indicate a low functioning thyroid (hypothyroidism). High basal body temperatures above 98.6 °F are less common but may indicate hyperthyroidism. Remember that the test must be conducted under optimal conditions in order to be an effective indicator of the thyroid state.

If you have questions or concerns contact your health care practitioner. This information is provided as reference material only. It is not meant to, nor should it take the place of professional guidance and help. This information is not intended as a substitute for advise, diagnosis or treatment by a healthcare professional. If you suspect you may have specific medical problems consult with your health care provider. Additionally, before starting any type of supplement/dietary regime consult with your health care practitioner first.


Kruzel, Thomas. Clinical Techniques: Thyroid Function Testing.

Murray, Michael N.D. & Pizzorno, J. N.D. 1998. Encyclopedia of Natural Medicine 2nd Ed. Prima Pub.