How can I exclude an irregular menstrual cycle from my average cycle length?

If you occasionally have irregular menstrual cycles, you can exclude such cycles from your average cycle length calculation by using Cycle Exclusion Rules on the My Preferences screen.

You can also use cycle rules to exclude special cycles, such as pregnancy or miscarriage. These are not, of course, menstrual cycles, but the tracking calendar will not know this and assume it's a very long cycle (from your period before pregnancy until the next period you record).

To exclude cycles that are longer than your usual cycle length, use the rule: Exclude menstrual cycles that are greater than {you select} days.

To exclude cycles that are shorter than your usual cycle length, use the rule: Exclude menstrual cycles that are less than than {you select} days.

For More Info: Click the help button on the My Preferences screen for additional help on menstrual cycle rules.


  1. Cycle rules are not used for constraining how you track your cycles using our Menstrual or Period Calendar. With those tools, you can record your period whenever it occurs, and if your cycles are irregular.

  2. Cycle rules are designed to handle occasionally irregular cycles, or special cycles such as pregnancy or miscarriage, so that your average menstrual cycle length calculation, which is used by many of our other tools (e.g. calculators, reminders), are not adversely affected.

Disclaimer: All information provided is for educational purposes only. It is not intended as a substitute for advice provided by a medical doctor or qualified healthcare provider. You should not use this information for self-diagnosis or for treating a health problem or disease. If you have any questions whatsoever about your medical health or believe you have a medical problem or disease, you should contact your medical doctor or healthcare provider. You should never disregard medical advice or delay seeking medical advice or treatment because of something you have read in this glossary. No guarantee is made about the accuracy, completeness, or relevance of the information contained herein.