Conception Calculator
Free conception date calculator to estimate when you conceived based on due date, last menstrual period, or ultrasound measurements.
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Calculate Your Conception Date
Wondering when you conceived? This calculator estimates your conception date and fertile window based on your due date or last menstrual period. Understand when pregnancy likely began.
Understanding Conception Timing
Conception occurs when sperm fertilizes an egg, typically within 24 hours of ovulation. Ovulation usually happens about 14 days after the first day of your last menstrual period (in a 28-day cycle). Sperm can survive up to 5 days in the reproductive tract, so the fertile window extends from 5 days before to 1 day after ovulation.
Conception Date Estimate
Conception ≈ LMP + 14 days (adjusted for cycle length)How to Use This Calculator
Using Conception Date Information
Pregnancy Dating
Verify or estimate pregnancy dating when LMP is uncertain.
Family Planning
Understand your fertile window for future pregnancy planning.
Medical Records
Provide estimated conception information to healthcare providers.
Frequently Asked Questions
No—conception is estimated within a range. Sperm can fertilize an egg for up to 5 days after intercourse, and the exact moment of fertilization can't be determined without IVF tracking.