Basal Body Temperature chart is a way commonly used to determine the time of ovulation. The basal body temperature refers to the temperature of your body at rest. You will need a special thermometer or ovulation thermometer and graph papers or a special chart. To determine your BBT, record your temperature everyday upon awakening before you get out of bed. Immediately after ovulation there will be a slight (no more than 0.4 to 1.0 degree Fahrenheit) but definite rise in your body temperature. Temperatures remain elevated until the next menstrual period.

Prior to ovulation, a woman's basal body temperatures generally range from 97.0 to 97.5 degrees Fahrenheit. Temperatures are suppressed at this time due to the presence of the hormone estrogen. After ovulation, due to the production of the heat-inducing hormone progesterone, temperatures rise to about 97.6 to 98.6 F. This rise in temperature indicates that ovulation has occurred. Your most fertile day is the one immediately before the rise in temperature. This method can be best utilized along with other fertility signs such as a pain or ache felt on one side of the lower abdomen, to be accurate. When a woman is pregnant, her temperature remains elevated throughout pregnancy. This test can also be used to know whether a woman is ovulating or not. If ovulation does not occur the normal temperature remains static always.