Pregnancy Due Date Calculator
Calculate your due date, current pregnancy week, trimester, and important milestones
Pregnancy Information
Quick Examples
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Select a calculation method and enter the relevant date to estimate your due date and pregnancy timeline.
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Pregnancy Milestones
Pregnancy Progress
How we calculated this
About Pregnancy Due Date Calculation
What Is a Due Date Calculator?
A pregnancy due date calculator estimates your expected delivery date based on key dates such as your last menstrual period (LMP), conception date, or IVF transfer date. The standard pregnancy lasts about 280 days (40 weeks) from the first day of your last period.
How Is It Calculated?
For LMP-based calculation, Naegele's rule adds 280 days (40 weeks) to the first day of your last menstrual period. For conception-based calculation, 266 days (38 weeks) are added. For IVF, the transfer date is adjusted by the embryo age at transfer and then 266 days are added.
Important Disclaimer
This calculator provides an estimate. Only about 5% of babies arrive on their exact due date. Your healthcare provider will give you a more accurate assessment based on ultrasounds and clinical examinations.
Authoritative sources and references
The official standards, guidelines, and research behind this calculator's methodology.
Pregnancy Due Date FAQ
How accurate is the due date estimate?
LMP-based estimates are accurate to within about 1-2 weeks for most women. Ultrasound dating in the first trimester is more precise, especially if your cycle length varies.
What if I don't know my last menstrual period date?
If you're unsure of your LMP, an early ultrasound is the most reliable way to determine gestational age. You can also use the conception date if you know it, or the IVF transfer date if applicable.
Can my due date change during pregnancy?
Your doctor may adjust your due date based on ultrasound measurements, especially during the first trimester. However, after the first trimester, due dates are rarely changed significantly.
How is the due date calculated from conception or IVF dates?
Gestational age runs from the last menstrual period, about two weeks before conception, so due date is conception date + 266 days (38 weeks). For IVF, day-5 embryo transfer due date is transfer date + 261 days; day-3 transfer is + 263 days — the calculator handles each mode.
What does "full term" actually mean?
Under the ACOG-standard labels, 37–38 weeks is early term, 39–40 weeks is full term, 41 weeks is late term, and 42+ is postterm. Births between 39 and 40 weeks 6 days have the best outcomes on average, which is why scheduled deliveries are generally planned in that window.
How many weeks pregnant am I right now?
Enter the first day of your last menstrual period and count from there — clinical gestational age includes the two pre-ovulation weeks, so a person with a 6-week-old embryo from conception is called 8 weeks pregnant. The calculator reports this clinical convention your provider uses.
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