Pregnancy Due Date Calculator
Estimate a pregnancy due date from last period, IVF transfer, or ultrasound dating, plus pregnancy week and trimester context.
Disclaimer: This calculator provides educational estimates only. It is not medical advice, diagnosis, contraception guidance, or a substitute for a qualified healthcare professional.
Pregnancy Due Date Calculator
A pregnancy due date calculator estimates the expected due date from the first day of the last menstrual period, an IVF embryo transfer, or an ultrasound dating scan. It also shows current pregnancy week and day, trimester timing, and key milestone dates.
The calculator is educational only. A clinician may confirm or revise the due date based on IVF records, early ultrasound, or other clinical information.
How to Use the Pregnancy Due Date Calculator
- Choose whether you want to calculate from last period, IVF transfer, or ultrasound dating.
- Enter the requested date information.
- If you are using the last-period method, you can optionally compare it with an ultrasound estimate.
- Review the estimated due date, pregnancy week, and trimester context.
- Use the timeline as general planning support, not as a substitute for prenatal care.
Formula Used
Due date from last menstrual period = LMP + 280 days
Due date from IVF transfer = transfer date + (266 - embryo age in days)
Due date from ultrasound = scan date + (280 - gestational age at scan days)
Estimated conception from LMP = estimated LMP + 14 days
If you compare a last-period estimate with an ultrasound, the calculator also checks common ACOG redating thresholds to see whether the due date would usually be changed.
Example
If your last period started on June 1, 2026, the estimated due date is March 8, 2027. If you had a day-5 embryo transfer on June 20, 2026, the estimated due date is March 8, 2027. If an ultrasound on July 20, 2026 shows a gestational age that points to a different date, the ultrasound estimate may become the preferred dating method.
What Your Result Means
A due date is an estimate, not a guarantee of delivery on that exact day. Pregnancy dating is used to give general timing context for prenatal care, screening, and milestone tracking.
Accuracy and Limitations
Cycle timing can vary, ovulation may not happen exactly on the expected day, and later ultrasounds are less reliable for dating than earlier ones. IVF dates and early ultrasound often provide stronger dating evidence than last-period recall alone. Always follow guidance from a qualified healthcare professional for medical decisions.
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Methodology and Disclaimer
This calculator uses standard gestational-age date math with educational redating support. It is not medical advice, diagnosis, contraception guidance, or a substitute for a qualified healthcare professional.
FAQ
How is a due date calculated from LMP?
The calculator adds 280 days to the first day of the last menstrual period.
How is a due date calculated from IVF transfer?
The calculator adds 266 days minus the embryo age in days to the transfer date.
How is a due date calculated from ultrasound?
The calculator adds the remaining gestational days up to 280 to the ultrasound date.
Can my due date change?
Yes. A clinician may adjust the due date based on IVF records or ultrasound dating, especially when the difference is large enough to cross accepted redating thresholds.
Is this due date medical advice?
No. It is an educational estimate and should not replace prenatal care.