July 2026
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Ovulation calculator
Estimate ovulation date and the days where conception is most likely.
Estimate, not a diagnosis. This tool gives an educational estimate based on the numbers you enter. It cannot account for your individual health history — consult a healthcare professional for anything clinical.
How this works
We estimate ovulation by subtracting a typical luteal-phase length (14 days) from the expected next period. The fertile window is computed as the five days before ovulation plus ovulation day itself.
Inputs
- First day of last menstrual period
- Average cycle length (days)
Outputs
- Estimated ovulation date
- Fertile window range
Limitations & guidance
Estimates are population-level. Use ovulation tests (LH) or temperature charts for more personalized tracking. Consult a clinician for fertility concerns.