Conception Date Calculator
Estimate when conception likely occurred based on your due date, last period, or ultrasound results.
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Estimated delivery date from your healthcare provider
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Frequently Asked Questions
How accurate are conception date calculations?
Conception date accuracy depends on the method used. Ultrasound dating (especially first trimester) is most accurate within 3-5 days. Due date calculations are moderately accurate within 7 days. Last menstrual period calculations assume a standard 28-day cycle with ovulation on day 14, which may not apply to all women. Remember that conception typically occurs during a 6-day fertile window, so exact timing can vary even with perfect information.
Why is there a range of possible conception dates?
Conception doesn't happen instantly - it's a process that occurs over several days. Sperm can survive in the female reproductive tract for up to 5 days, while the egg is viable for 12-24 hours after ovulation. This creates a fertile window where conception could occur. Additionally, ovulation timing can vary between cycles, and the exact moment of fertilization is impossible to pinpoint without medical intervention. The range accounts for these biological variables.
Medical Disclaimer
This conception calculator provides estimates for educational purposes only. Actual conception dates can vary due to individual cycle differences, ovulation timing variations, and other biological factors. These calculations should not be used for legal purposes, paternity determination, or critical medical decisions. For accurate gestational age assessment and prenatal care timing, always consult with your healthcare provider who can use medical dating methods like ultrasound measurements.