Basal Body Temperature (BBT) Chart Tips and Download

Taking Your Basal Body Temperature
Your basal body temperature (BBT) changes throughout the month according to where you are in your cycle. Tracking your BBT helps you determine when you’re most fertile.

  • Before ovulation, your BBT is usually about 96 F to 98 F
  • During ovulation, your body releases the hormone progesterone. This raises your BBT by 0.4 to 0.8 degrees a day or two after ovulation
  • This rise in temperature usually lasts until your period starts
  • If you become pregnant, your temperature will stay elevated during your pregnancy. After charting for a couple of months, you may see a pattern emerge
  • You’re most fertile two to three days before ovulation, and 12 to 24 hours after ovulating
  • Sperm can live up to six days in a woman’s body. So your best chance for conception is to have sex a few days before you ovulate

BBT charting is widely used, but it’s not foolproof.

  • Some women may not see a clear pattern
  • You may ovulate at different times in your cycle from one month to the next. This can make it hard to predict

Tips for Taking Your Basal Body Temperature

  • You’ll need a basal body thermometer. You can find them at most pharmacies. A regular one can’t detect such a small change in temperature
  • Keep the thermometer, paper, and pencil by your bedside
  • Take your temperature the same time every morning while still in bed
  • Don’t do anything before your measuring your BBT. Don’t eat, drink, smoke, get up, or move around
  • You can take your temperature orally, rectally, or vaginally. Do it the same way every time
  • Make your own graph, or find one online. There are also iPhone and Android phone apps available
  • Your doctor can help you interpret your chart

Cervical Mucus and Your Menstrual Cycle
The mucus made by your cervix changes at certain times during your cycle. You can predict ovulation by noting these changes. Using this and BBT together may be more effective than using just one method, though it’s still not foolproof.
Mucus released by the cervix serves different purposes.

  • It prevents sperm from getting into the uterus when you aren’t ovulating
  • It protects sperm and helps it along on its journey toward the egg when you are ovulating

Here’s a typical pattern of cervical mucus changes for a woman with a 28-day cycle:

  • Days 1-5: You get your period
  • Days 6-9: Vagina is dry with little to no mucus
  • Days 10-12: Sticky, thick mucus appears, gradually becoming thinner and whiter
  • Days 13-15: Mucus becomes thin, slippery, stretchy, and clear, similar to the consistency of egg whites. This is the most fertile stage
  • Days 16-21: Mucus becomes sticky and thick again
  • Days 22-28: Vagina dries

Check your cervical mucus several times a day.

  • Be sure your hands are clean
  • Rub some toilet paper or your fingers over the opening of your vagina. You should be able to see your cervical mucus
  • Note the color and consistency between your fingers

Write it down on your fertility chart.