Get your IVF due date from your embryo transfer date or egg retrieval date, day-3, day-5 or day-6 transfers, fresh or frozen, plus your equivalent last period, gestational age today and the term window.
| Input | Result |
|---|---|
| Day-5 blastocyst transfer on 10 March 2026 | Estimated due date 26 November 2026 |
| Day-3 transfer on 10 March 2026 | Estimated due date 28 November 2026 |
| Egg retrieval on 10 March 2026 | Estimated due date 1 December 2026 |
A natural-conception due date works backwards from the first day of your last period and assumes ovulation on day 14, an assumption that is wrong for a lot of people. IVF dating removes the guesswork, because the laboratory knows exactly how old the embryo was on the day it was transferred.
Everything follows from one rule. Convert the transfer date into an equivalent last menstrual period, then add the standard 280 days:
equivalent LMP = transfer date − (14 + embryo age in days)
due date = equivalent LMP + 280 days
which is the same thing as adding a fixed number of days to the transfer date:
| Starting point | Days to add | Why |
|---|---|---|
| Egg retrieval (day 0) | 266 | Retrieval stands in for ovulation, 14 days into a 280-day pregnancy |
| Day-5 embryo transfer | 261 | 266 − 5, the embryo is already five days old |
| Day-3 embryo transfer | 263 | 266 − 3 |
| Day-6 embryo transfer | 260 | 266 − 6 |
Clinical reference: ACOG Committee Opinion No. 700, Methods for Estimating the Due Date.
More reliable than any other method, because the inputs are recorded rather than recalled. IVF pregnancies rarely need a dating scan to establish the timeline, the scan confirms the dates rather than setting them, and where a scan and the IVF dates differ by only a day or two, the IVF date usually stands.
But a due date is still a median, not a deadline. Roughly one baby in twenty arrives on the date itself, most babies come between 37 and 41 completed weeks, and the term window shown above is the range that actually matters for planning. Multiples, more common after IVF — usually arrive earlier than a singleton would.
Not medical advice. This calculator does date arithmetic on the dates you enter, nothing more. It does not diagnose, does not assess a pregnancy and cannot account for your individual history. Your fertility clinic or midwife sets your official dating, and ultrasound findings can override any calculation. If anything here conflicts with what your care team told you, theirs is the date that counts.
You work from the age of the embryo instead of a guessed ovulation date. The general rule is due date = transfer date + 266 − embryo age in days: 261 days for a day-5 blastocyst, 263 for a day-3 embryo, and 266 days from an egg retrieval because retrieval stands in for ovulation.
Because a standard calculation assumes a 28-day cycle with ovulation on day 14, which is wrong for many people, and especially for people who needed fertility treatment. With IVF the clinic records the retrieval date and the embryo's age, so there is no ovulation guesswork at all.
No. Dating depends on the embryo's developmental age on the day of transfer, not on how long it spent frozen. A blastocyst frozen at day 5 is still dated as a day-5 transfer, so the arithmetic is identical to a fresh transfer.
Because gestational age is counted from an equivalent last menstrual period, roughly two weeks before conception. It keeps IVF pregnancies on the same clock as everyone else's, so screening windows and the definition of term line up.
You can, but it will ask for your last period and assume ovulation on day 14, exactly the assumption IVF makes unnecessary. Entering your transfer date here gives a date anchored to what actually happened.