IVF / FET Due Date Calculator
Enter your embryo transfer date and embryo age to get an IVF or FET-specific due date, more precise than a standard LMP-based estimate.
*Estimates only, not medical advice. Your fertility clinic's dating is the authoritative source for your due date.
Expecting naturally instead? Use standard LMP-based dating.
Pregnancy Due Date Calculator👶 IVF Due Date Math
Why fertility clinics date IVF/FET pregnancies differently from natural conceptions.
How it Works
Instead of estimating ovulation from your last menstrual period, IVF and FET dating starts from a known fact: the exact date the embryo was placed in the uterus, and its exact age (Day 3, 5, or 6) at that moment.
The Formula
Due Date = Transfer Date + (280 - Embryo Age in Days). A Day 5 transfer adds 275 days; a Day 3 transfer adds 277 days, because the embryo is already that many days old at transfer.
Pro Tip
Your clinic will typically confirm and possibly adjust your due date after your first dating ultrasound around 6-8 weeks. Treat this calculator as a helpful early estimate, not a final answer.
Frequently Asked Questions
Why is the IVF due date calculated differently from a natural pregnancy? +
A natural pregnancy due date is usually estimated from the first day of your last menstrual period (LMP), assuming ovulation around day 14. With IVF or FET, you know the exact age of the embryo at transfer, which removes the guesswork around ovulation timing and makes the estimate more precise.
What is the difference between a Day 3 and Day 5 embryo transfer? +
A Day 3 embryo (cleavage-stage) is transferred 3 days after fertilization/retrieval, while a Day 5 embryo (blastocyst) is transferred 5 days after. Because the embryo's age is known precisely, the due date formula subtracts that age from the standard 280-day pregnancy length from the transfer date.
How is the due date formula derived? +
A full-term pregnancy is estimated at 280 days (40 weeks) from the last menstrual period. For IVF/FET, due date = transfer date + (280 - embryo age in days), accounting for the embryo already being 3 or 5 days old at the moment of transfer.
Is the IVF due date more accurate than a standard due date? +
Generally yes. Because the fertilization date and embryo age are known exactly, IVF and FET due dates tend to have less uncertainty than dates calculated purely from menstrual cycle history.
Does this calculator apply to fresh IVF transfers as well as frozen (FET)? +
Yes. The same formula applies to both fresh IVF transfers and frozen embryo transfers (FET) — what matters is the transfer date and the embryo's age at transfer (typically Day 3 or Day 5), not whether the embryo was fresh or previously frozen.
Should I trust this calculator over my clinic's dating? +
No — always defer to your fertility clinic and OB/GYN, who confirm dating with ultrasound measurements. This tool is meant for quick, informal estimates only.