Ovulation & Fertile Window Calculator
Track your ovulation day and fertile window to help plan your pregnancy journey.
Let's find out
When do you ovulate?
Typical range: 21 - 35 days
Your fertility window awaits
Enter your details to see your ovulation & fertile days
How is ovulation calculated?
Ovulation typically occurs about 14 days before your next period. We subtract 14 from your cycle length to estimate which day of your cycle you ovulate.
What is the fertile window?
The fertile window spans the 5 days before ovulation and ovulation day itself. Sperm can survive up to 5 days, so conception is possible during this entire window.
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Common Questions
- How do I calculate my ovulation day?
- Ovulation typically occurs 14 days before your next expected period. For a 28-day cycle, that's around day 14. For a 30-day cycle, it's around day 16. Tracking basal body temperature and cervical mucus changes provides more precise timing than calendar counting alone.
- What is the fertile window?
- The fertile window spans roughly 6 days — the 5 days before ovulation plus ovulation day itself. Sperm can survive up to 5 days in the reproductive tract, while the egg lives only 12-24 hours after release. The highest conception probability is 1-2 days before ovulation.
- How accurate are ovulation calculators?
- Calendar-based ovulation calculators provide an estimate based on average cycle length. They're most accurate for people with regular cycles. For irregular cycles, ovulation predictor kits (OPKs) that detect the LH surge are significantly more reliable.
For educational purposes only — not a substitute for professional medical advice. Always consult your pediatrician with questions about your child's health.