IVF due date calculator

Work out your estimated due date from an embryo transfer or egg retrieval — the most precise dating there is, because the timing is known. Runs in your browser; nothing is saved.

How to use it

How IVF dating works

Every IVF date converts to an equivalent last period, after which the usual 280-day rule applies. A day-5 blastocyst transfer adds 261 days to the transfer date; a day-3 transfer adds 263; an egg retrieval adds 266. The full reasoning is in IVF due date calculation.

Worked example

A day-5 embryo transferred on 1 February gives an estimated due date of about 20 October the same year (transfer + 261 days).

Accuracy and limitations

Because the timing is exact, IVF dating rarely needs adjusting, though a scan still confirms development. If a scan and the IVF date disagree only slightly, the IVF date usually stands — see how accurate is your due date. Your fertility clinic confirms your dating.

Frequently asked questions

How is a due date calculated after a day-5 embryo transfer?

Add 261 days to the transfer date. That equals an equivalent last period of the transfer date minus 19 days, plus the standard 280-day pregnancy.

Is IVF gestational age calculated from the transfer date?

Effectively, yes — the transfer date and embryo age give an equivalent last period, and gestational age counts from there. So an IVF pregnancy is already about two weeks along at transfer.

Why can IVF dating differ from LMP dating?

IVF timing is known exactly, so it doesn’t rely on a remembered last period or an assumed ovulation day. That makes IVF dating more precise than last-period dating.

Is a frozen embryo transfer dated differently?

No. Dating depends on the embryo’s age at transfer (day 3 or day 5), not on whether it was frozen. A day-5 blastocyst is dated the same way fresh or thawed.

What if I only know the egg retrieval date?

Choose “egg retrieval” and the tool adds 266 days — retrieval counts as day 0, the equivalent of conception.

Last meaningfully updated: 2026-08-25.