health calculator
Estimate ovulation date and fertile days.
Save this page to recalculate fertile windows and plan ovulation tracking.
Days until ovulation
5 days
Formula
Ovulation day = cycle length - 14This common estimate assumes ovulation occurs around 14 days before the next period.
Step by step
Example
In a 28-day cycle on day 9, ovulation is estimated around day 14, about 5 days away.
Related guides
Guide
Track your ovulation cycle with calendar methods, basal body temperature, cervical mucus, and ovulation predictor kits to identify your most fertile days.
Guide
Understand conception timing, how sperm and egg viability affect fertility windows, and how to use ovulation tracking for planning or preventing pregnancy.
Summary
Days to ovulation
5 days
Countdown to ovulation.
Current cycle day
Day 9
Position in current menstrual cycle.
Ovulation day
Day 14
Estimated release day.
Fertile window
Days 9-15
Peak fertility window.
D3 visualization
Compare the relative duration of your peak fertility window vs other cycle days.
D3 visualization
Check completed cycle days relative to your estimated ovulation day.
Guide
The ovulation calculator estimates the day of ovulation and the fertile window based on the start of your last period and cycle length. Widespread guidelines state that ovulation occurs 14 days before the start of the next cycle.
Fertility indicators
Physical markers like temperature and fluid shifts that signal ovulation.
The fertile window typically lasts about 6 days, including the 5 days before ovulation and the day of ovulation itself.