How to interpret your chart

How to interpret your chart

How easy it is to understand and interpret your chart depends on the reliability and accuracy of the data you enter and the clarity of your chart pattern.

Some charts are easy to interpret while others require a bit of extra analysis and flexibility. 

But don’t panic or give up. With each cycle you chart, interpreting your charts will become increasingly easier.

Detecting ovulation

An ideal chart pattern shows all your fertility signs (primary and secondary) lined up to suggest the same ovulation date.

In this case, detecting ovulation is fairly straightforward: 

  1. Your cervical fluid has dried up.
  2. You observe a thermal shift on your chart of three days or more where temperatures are higher than the previous several temperature points for at least three days.

If this is true for you then ovulation can be detected for the day before your temperature shifted. 

After the three days of higher temperatures, ovulation is shown on the chart with a vertical red line crossing the chart on the cycle day of ovulation.  At this time, a cover line (a red horizontal line) is also drawn on your chart as a visual tool to help you see the ovulation (biphasic) pattern. When the cycle pattern is clear, the cover line will usually be higher than most of your pre-ovulation temperatures and lower than most of your post-ovulation temperatures. The cover line has no physiological meaning and is only used as a visual tool to help you see your chart pattern. 

When are you fertile?

You should consider yourself fertile and continue to have intercourse until a clear thermal shift is observed on your chart.

Chart patterns are not always perfectly clear so sometimes a bit of extra interpretation and flexibility is needed. If ovulation cannot be clearly determined on your chart, it is recommended to keep on considering that you could be fertile.