Medical Disclaimer

Last updated: October 22, 2026

Estimates only

Periodly's period, ovulation, fertile-window, and due-date calculations are statistical estimates based on the dates and cycle lengths you enter, combined with general population averages. They are not medical advice, diagnosis, or treatment, and they cannot account for individual medical conditions, medications, or hormonal factors that affect your cycle.

Not a contraceptive method

Ovulation and fertile-window predictions must never be used as a method of birth control. Ovulation timing can shift unpredictably due to stress, illness, travel, medication, and many other factors. If you need reliable contraception, speak with a healthcare provider about proven methods.

When to seek professional care

Consult a doctor or qualified healthcare provider if you experience very short or long cycles, missed periods without pregnancy, heavy bleeding, severe pain, or any symptoms that concern you. Do not delay seeking care because of anything shown on this site.