IVF Due Date Calculator
IVF dating is exact, because the embryo’s age is known.
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The one pregnancy dating that is not an estimate
Almost all pregnancy dating works backwards from an assumed ovulation date, which is why it carries a week of uncertainty. IVF is the exception: the embryo's exact age is known, because fertilisation happened in a laboratory at a recorded time. That removes the largest source of error in obstetric dating entirely.
The arithmetic runs from gestational age at transfer. Conception is conventionally treated as gestational day 14, so a day-5 blastocyst is already 19 days of gestational age the moment it is transferred, and the due date is 261 days later. A day-3 embryo is 17 days, giving 263 days. A day-6 blastocyst is 20 days, giving 260.
Frozen transfers use the same logic, dating from the transfer rather than from the original egg retrieval — time in storage does not count toward gestational age. IVF due dates are typically accurate enough that later ultrasounds rarely change them, which is the reverse of the usual situation where scan dating overrides LMP dating. Your clinic's own figure should always take precedence, since it reflects the actual recorded timings.
Medical disclaimer. This calculator is for general information and education only. It is not medical advice, not a diagnosis, and not a substitute for professional care. Your fertility clinic’s own dating reflects the actual recorded timings of your cycle and takes precedence over any general calculation.Speak to a doctor or another qualified clinician about any health decision.Last reviewed .
Frequently asked questions
Why is IVF dating more accurate?
Because the embryo\’s age is known exactly rather than inferred. Conventional dating assumes ovulation on day 14 of a regular cycle, which introduces roughly a week of uncertainty. IVF removes that assumption entirely.
How does transfer day change the due date?
Each day of embryo age shifts the due date by one day. A day-3 transfer gives 263 days from transfer, day-5 gives 261, and day-6 gives 260 — because an older embryo is further along at the moment of transfer.
Does a frozen transfer date differently?
No, the same logic applies from the transfer date. Time in storage does not count toward gestational age, so a frozen day-5 blastocyst is dated exactly as a fresh one would be from its own transfer date.
Will a scan change my IVF due date?
Rarely. IVF dating is usually accurate enough that ultrasound confirms rather than revises it — the opposite of the usual situation, where scan dating overrides dating from a last period.
What gestational age am I at transfer?
A day-5 blastocyst is 2 weeks and 5 days, because conception is conventionally counted as gestational day 14. This is why an IVF pregnancy is already several weeks along on the day of transfer.