Fertility Calculator
Maps your last period and cycle length to a rough fertile window using common textbook timing (ovulation about two weeks before the next expected period). Optional regularity notes explain how much to trust the dates.
This is not fertility treatment planning. Medication cycles, PCOS, recent birth or miscarriage, and perimenopause can all move real ovulation away from the calendar.
Same “Day 1” definition as a typical period tracker.
Count from Day 1 to the next Day 1. If unsure, 28 is a common default.
Helps you interpret how firm the date window is.
Select your last period start date to see a suggested window.
More cycle tools
Compare with the fertile window calculator and IVF timelines where medically relevant—they answer different questions than this simplified planner.
Important usage notes & limitations
Reproductive timelines interact with contraception cessation, PCOS phenotype, transgender hormone therapy intensity, low body-fat athletic amenorrhea, and perimenopause. Hormonal contraception intentionally suppresses natural ovulatory signals until washout stabilization — calendar methods become meaningful only once cycles resume reliably.
See also: Pregnancy Due Date Calculator · Women's health calculators hub.