Ovulation Calculator
Estimate your ovulation date and fertile window based on your menstrual cycle length and last period date.
Select your last period date.
How Ovulation is Estimated
Ovulation day ≈ LMP + (Cycle length − 14)
Ovulation typically occurs about 14 days before the next period. The fertile window spans approximately 5 days before ovulation through 1 day after.
Important Notes
- This is an estimate based on average cycle patterns.
- Actual ovulation varies and can be confirmed with ovulation predictor kits or basal body temperature tracking.
- Sperm can survive up to 5 days, so the fertile window starts before ovulation.
Disclaimer: This tool provides estimates only. It should not be used as a sole method of contraception or fertility planning. Consult your healthcare provider.
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Last updated: 2026-08-08