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Conception Date Calculator
Find out when you likely conceived
How Conception Date Is Calculated
Conception occurs when a sperm fertilizes an egg, typically around ovulation day. For most women with a 28-day cycle, this is approximately 14 days after the first day of the last menstrual period.
Our calculator uses two approaches:
- From LMP: Conception date = LMP + 14 days (adjusted for cycle length)
- From due date: Conception date = Due date - 266 days
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Frequently Asked Questions
How is a conception date calculated?▾
Conception typically occurs about 14 days after the first day of your last menstrual period (LMP), assuming a standard 28-day cycle. If your cycle is longer or shorter, the ovulation day shifts accordingly. If you know your due date, conception is estimated at about 266 days (38 weeks) before it.
Can I know the exact date I conceived?▾
Unless you tracked ovulation precisely (with OPKs, BBT, or IVF), the exact conception date is an estimate. Sperm can survive up to 5 days in the reproductive tract, so conception could have occurred on the day of intercourse or up to 5 days later when ovulation happened.
Is conception date the same as the date I had intercourse?▾
Not necessarily. Conception happens when sperm fertilizes an egg, which occurs at ovulation. Since sperm can live up to 5 days, intercourse days before ovulation can still result in conception on the ovulation day.
How accurate is a conception date calculator?▾
Conception date calculators provide an estimate based on standard ovulation timing. The actual date can vary by several days. For the most accurate dating, an early ultrasound (6-9 weeks) can measure the embryo and estimate conception more precisely.
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Medical Disclaimer
This calculator provides estimates based on standard medical formulas, including Naegele's Rule. The results are approximations and should not be considered a substitute for professional medical advice, diagnosis, or treatment.
Every pregnancy is unique. Due dates are estimates — only about 5% of babies are born on their exact due date. Your healthcare provider may adjust your due date based on ultrasound measurements and other clinical factors.
Always consult with your obstetrician, midwife, or healthcare provider for personalized medical guidance throughout your pregnancy.