Pregnancy Conception Calculator
Estimate your likely conception date and fertile window from your last period or a known due date.
Default is 28 days
Estimated conception date
June 29, 2026
This is an estimate based on average cycle timing, not a medical diagnosis. Actual ovulation timing varies from person to person.
What Your Result Means
Conception typically happens within about a day of ovulation, which for an average 28-day cycle falls around day 14. This calculator adjusts that estimate for your actual average cycle length.
How It Is Calculated
Conception date ≈ LMP + (cycle length − 14) days
Worked Example
With a last period starting January 1st and a typical 28-day cycle, estimated conception falls around January 15th.
Important Assumptions
- The fertile window shown accounts for sperm survival of up to 5 days before ovulation.
- Longer or shorter cycles shift the estimated conception date later or earlier, respectively.
- This is a statistical estimate, not a precise measurement - actual ovulation timing varies cycle to cycle.
Frequently Asked Questions
- How does cycle length affect the estimate?
- Ovulation generally occurs about 14 days before your next period, regardless of cycle length. So a longer cycle pushes the estimated conception date later, and a shorter cycle pulls it earlier.
- Can I use this to find out my baby's gender or paternity window?
- This calculator only estimates timing for pregnancy planning purposes. For anything related to legal or medical matters, consult a healthcare provider.
Related Calculators
Methodology
This calculator estimates ovulation timing based on average cycle length. See our methodology page for details.
This calculator provides estimates for educational purposes only. It does not provide medical diagnosis and is not a substitute for professional medical advice. Consult a qualified healthcare provider about your health.