IVF due date calculator

From the transfer date plus the embryo's known age, per ACOG Committee Opinion 700. The underlying rule is that a due date is 266 days (38 weeks) from conception. In IVF the embryo was already 5 days old at a blastocyst transfer, so the due date is 266 − 5 = 261 days from the transfer; a day-3 embryo gives 266 − 3 = 263 days. If you'd rather count from your egg retrieval (the day of fertilization) or an IUI, both stand in for the conception day itself, so it's the full 266 days. This tool then converts your due date into a standard 'effective last period' anchor, so your weeks, trimester, and milestone dates line up with what your clinic and every pregnancy app report.

No. Fresh or frozen makes no difference to the calculation, and this is a common point of confusion. The embryo's development is paused while it's frozen, so what matters is its age when it was transferred, not when it was created. A day-5 blastocyst frozen for two years is still a day-5 blastocyst on transfer day, and the due date is still 261 days from that transfer. Enter your actual transfer date — the day the embryo went back — and the embryo's day (3 or 5), and the math is identical for fresh and frozen cycles.

Because the one thing every other dating method has to estimate — when conception happened — is known to the day in IVF. Dating from a last menstrual period assumes a textbook 28-day cycle and day-14 ovulation, which is the single biggest source of due-date error. Even an early ultrasound is a measurement with a margin of error. With IVF, the lab knows exactly when the egg was fertilized and exactly how old the embryo was at transfer, so ACOG's guidance is that an ART-conceived pregnancy should be dated from those ART dates. That's why an IVF due date usually needs no correction later.

Theirs. Your provider's due date is the one of record — it's what your prenatal schedule, screening windows, and any delivery decisions are keyed to. Small differences usually come down to rounding conventions, a day-6 blastocyst entered as day 5, or a clinic dating from retrieval rather than transfer. If the gap is more than a couple of days, it's worth asking your clinic how they calculated it, since ART dating rarely gets revised. Use this tool to understand the math and preview your milestones, then treat the date in your chart as the official one.

The same formula covers it: due date = transfer date + 266 days − the embryo's age at transfer. A day-6 blastocyst works out to 260 days from transfer and a day-7 to 259 — one or two days earlier than a day-5, which is within the noise of any pregnancy timeline. Some clinics simply date day-6 and day-7 transfers as if they were day-5, which is also fine; ask yours which convention they use. This calculator offers day-5 and day-3 (the overwhelming majority of transfers), and your clinic's stated due date wins if it differs.

Completely. This calculator runs entirely in your browser: the dates you enter are never sent to a server, stored, or shared, and using it tells us nothing about you. Close the tab and everything is gone. We treat reproductive and fertility data as sensitive by default — in a post-Dobbs world that isn't a nicety, it's the design requirement. It's an educational estimate based on published ACOG methods, not medical advice or a diagnosis; your clinic and OB confirm your dates.