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Charting Basal Body Temperature: How to Chart Yours

Katlyn Joy |11, August 2011


When attempting to conceive, an awareness of when your most fertile days occur and the patterns of your own cycle is crucial. One of the best tools in your trying to conceive arsenal is the basal body temperature chart. This handy little chart is free and simple to use. The hardest thing about doing the basal body temperature chart is simply being consistent.

The chart itself is a small graph with a temperature reading on one side, going from about 96 or 97 degrees up to nearly 100 degrees. One the other side of the graph is an area is a number indicating what day of your cycle that space represents. Day one is the first day of your period.

Ovulation Basics

The average day of ovulation in a 28 day cycle is day 14. However, not all women have 28 day cycles and not all women will ovulate at day 14. For most women the days prior to ovulation will experience temperatures in the 96 to 98 degree range while post-ovulation temperatures generally range from 97 to 99 degrees.

For most women the temperature rise at ovulation will be about .2 degrees. This rise in temperature happens due to the hormone progesterone. Progesterone is secreted by the corpus luteum after the egg has been released.


Taking a basal body temperature will give you an idea of when ovulation is about to occur. Typically just prior to ovulation your temperature will dip slightly then peak again once ovulation has occurred. By faithfully charting your temperatures throughout your cycle you can get a good overall picture of your regular ovulation patterns and determine the days most likely to be successful in your pregnancy tries.


Take your basal body temperature first thing in the morning, ideally at the same or nearly same time each day. Don't get up and run to the bathroom, and don't eat or drink anything. Just keep your thermometer in easy reach and learn to roll off the pillow and grab the thermometer and record your findings immediately.


It's recommended that women purchase and use a special thermometer intended for recording basal body temps. The thermometer measures a bit more accurately as it shows degrees in tenths, helpful when you may be talking about differences as little as .3 degrees. Another option is to use a good digital thermometer.

You may take your temperature orally, vaginally or rectally but whatever method you choose you must stick with it in order for your results to be valid. Leave a glass thermometer in place for five minutes before recording your temperature.

Other Factors to Include on the Chart

Besides the day of the cycle and the temperature you should also include some additional information such as your observation of your cervical mucus on your basal body temperature chart. Describe your mucus as sticky, thick, runny, dry, white, stringy or clear for instance.
Note any special considerations or concerns on the day if you think there are any factors affecting your temperature.

Things that Affect your Basal Body Temperature

  • Drinking alcohol the night before will raise your BBT.
  • Stress
  • Illness or infection
  • Some medications
  • Air travel/jet lag
  • Coffee/caffeine
  • Dieting
  • Exercise

Tips for Successful Charting

- Make sure you start accurately by charting day one as the actual first day of menstrual flow.
- Don't chart light spotting that precedes your period as the start of the cycle.
- Don't smoke prior to taking your basal body temperature.
- Use a downward pointing arrow or some other symbol on the chart to indicate days when intercourse occurs.
- Always use a new chart when a new cycle begins.

Tool: Fertility Chart
Track ovulation, basal body temperature (BBT) and cervical mucus, position, and firmness with Baby Corner's downloadable and printable fertility chart.

Related Articles

Charting Basics: Basal Body Temperature

What Will Your Fertility Chart Look Like If You Are Pregnant?

Cervical Mucus: Why it Matters and How to Chart It

Charting Cervix Position

Charting Basics - Cervical Fluid


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