Conception Calculator
Estimate your most likely conception date and fertile window for family planning.
Result
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A conception date calculator works backward from your due date to estimate when conception most likely occurred, which can help clarify pregnancy timing and early milestones.
Examples
Due date of October 1
Conception window: approximately January 6-14, most likely January 9. Estimated LMP: December 25. Implantation: around January 18.
Frequently Asked Questions
Why is the conception date a range?
Ovulation timing varies from woman to woman and cycle to cycle. Sperm can also survive 3-5 days in the reproductive tract, so intercourse before ovulation can still result in conception. This creates a window rather than an exact date.
How is conception date different from LMP date?
LMP (Last Menstrual Period) is the first day of your last period, about 2 weeks before ovulation and conception. Doctors date pregnancies from LMP because most women know this date, even though conception happens approximately 14 days later.
Result
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Quick Tips
- •Use the due date confirmed by your doctor or an early ultrasound for the most accurate conception estimate.
- •Remember that the conception window is a range — focus on the window rather than a single date.