Charting Your Basal Body Temperature
Use these instructions only if you are using a thermometer that measures your temperature in degrees Fahrenheit or Celsius.
To make a chart, get a piece of graph paper.
- At the top of your chart, write in a row of numbers. Leave the first square in the row blank, then write the numbers 1 through 45, one number in each square. These are the days of your menstrual cycle. Your cycle may be shorter than 45 days. If it is, you don't need as many numbers.
- On the left side of your chart, write a vertical column of numbers that represent your temperature, in tenths of a degree, on any given day. Start this column under the empty square next to the "day 1" square.
- If your thermometer is Fahrenheit: In the first square of your temperature column, write 99.0°. In the square under that, write 98.9°, then 98.8°, 98.7°, 98.6°, and so on, down to 97.0°.
- If your thermometer is Celsius: In the first square of your temperature column, write 37.5°. In the square under that, write 37.4°, then 37.3°, 37.2°, 37.1°, and so on, down to 36.0°.
The numbers across the top of the chart are the days of your menstrual cycle. The first day of your period is Day 1. Shade the box on the grid that matches your temperature for that day. Draw a line connecting the shaded squares so you can see your dips and spikes.
Current as of: February 23, 2022
Author: Healthwise Staff
Kathleen Romito MD - Family Medicine
Adam Husney MD - Family Medicine
Femi Olatunbosun MB, FRCSC - Obstetrics and Gynecology