IVF due date calculator.
Built for patients who just got a transfer date and need a clear EDD, beta window, and next milestones — not a blank worksheet.
Planning aid for family building — not medical, legal, or tax advice, and not a clinical opinion for your case.
An IVF due date is calculated from the day of fertilization: egg retrieval date plus 266 days, which works out to a day-3 transfer date plus 263 days or a day-5 transfer date plus 261 days.
Same Family-Building Lab engine as the Transfer-to-Baby Planner and surrogacy due date tools. Your Journey Passport keeps the date across pages on this device.
How the math works.
Every IVF due date comes from one number: 266, the average count of days from fertilization to birth. Because IVF tells you exactly when fertilization happened, the calculator never has to guess at ovulation the way a last-menstrual-period date does. It subtracts the embryo’s age at transfer from 266 and adds the remainder to your transfer date.
Gestational age runs on a different clock than embryo age. Pregnancy is conventionally counted from a stand-in last menstrual period 14 days before fertilization, so on the day of a day-5 transfer you are already 19 days pregnant on paper — embryo age (5) plus 14. That is why the calculator’s week count sits ahead of your days-since-transfer count.
This is the method-of-conception dating that the American College of Obstetricians and Gynecologists (ACOG) describes for pregnancies conceived through ART: when the fertilization date is known, the estimated due date is derived from it rather than from menstrual dating. The calculator applies that convention automatically and shows the formula it used under each result.
IVF due date FAQ.
Is an IVF due date more accurate than one from my last period?
Generally, yes. Dating from a last menstrual period assumes a textbook 28-day cycle with ovulation on day 14, while IVF removes the guesswork — the fertilization date is known to the day. Your clinic may still refine the estimate at an early ultrasound, and that clinical dating is the one that counts for your care.
Day 5 vs. day 6 transfer: does it change my due date?
By exactly one day. The formula subtracts the embryo’s age from 266, so a day-6 blastocyst adds 260 days to the transfer date instead of the 261 a day-5 embryo adds. The calculator supports day 6 and day 7 transfers with the same subtraction.
Do twins change the due date?
The calculated date itself does not move — due-date math assumes a singleton, 40-week convention. Multiples do tend to arrive earlier, so treat the calculator result as the far edge of the window and let your care team set the real planning dates.