Conventions vary between clinics, and frozen embryo transfers, donor eggs and different embryo ages follow the same logic but should be confirmed with your clinic. Early ultrasound measurements may adjust the date slightly. The tool is for information, and only your provider can set official dates.
Use the clinic-recorded transfer date and embryo age in days at that transfer. Day-3 and day-5 transfers are different calendar cases. The resulting estimated delivery date does not replace the treating clinician’s assigned obstetric dating.
IVF Due Date: worked example
| Embryo transfer date | June 1, 2026 |
|---|---|
| Embryo age at transfer (days) | Day 5 embryo |
| Estimated due date | February 17, 2027 |
| Gestational age on transfer day (days) | 19 |
IVF Due Date: formula
Common error: Counting 280 days from the transfer date. That ignores the days the embryo had already lived and the two weeks of dating before conception, and it lands nearly three weeks late.
IVF Due Date: changing Embryo transfer date
| Embryo transfer date | Estimated due date | Gestational age on transfer day (days) |
|---|---|---|
| May 18, 2026 | February 3, 2027 | 19 |
| May 25, 2026 | February 10, 2027 | 19 |
| June 1, 2026 (example) | February 17, 2027 | 19 |
| June 8, 2026 | February 24, 2027 | 19 |
| June 15, 2026 | March 3, 2027 | 19 |
IVF Due Date: compare input ranges
| Input | Tested from | To | Gestational age on transfer day (days): low input | Gestational age on transfer day (days): high input | Swing |
|---|---|---|---|---|---|
| Embryo age at transfer (days) | Day 3 embryo | Day 6 embryo | 17 | 20 | 3 (16%) |
| Embryo transfer date | May 25, 2026 | June 8, 2026 | 19 | 19 | 0 |
IVF Due Date: individual input comparisons
| Input | Value | Estimated due date | Gestational age on transfer day (days) |
|---|---|---|---|
| Embryo transfer date | May 18, 2026 | February 3, 2027 | 19 |
| May 25, 2026 | February 10, 2027 | 19 | |
| June 1, 2026 | February 17, 2027 | 19 | |
| June 8, 2026 | February 24, 2027 | 19 | |
| June 15, 2026 | March 3, 2027 | 19 | |
| Embryo age at transfer (days) | Day 3 embryo | February 19, 2027 | 17 |
| Day 5 embryo | February 17, 2027 | 19 | |
| Day 6 embryo | February 16, 2027 | 20 |
IVF Due Date: values and definitions
| Quantity and definition | Value used |
|---|---|
| Embryo transfer date | June 1, 2026 |
| Embryo age at transfer (days) — Day 3 and day 5 embryos are the most common. | Day 5 embryo |
| Estimated due date | February 17, 2027 |
| Gestational age on transfer day (days) | 19 |
Ultrasound measurements and transfer records supply different evidence
The University of Cincinnati's published 2015 dating protocol assigns an assisted-reproduction due date from the treatment-derived gestational age. Its first-trimester ultrasound recommendations specify the mean of three separate crown-rump-length measurements in a true midsagittal plane. Mean gestational-sac diameter is not recommended for estimating the delivery date.
Those are different measurements with different purposes; a sac measurement cannot simply replace crown-rump length in a dating rule. The transfer-date calculation needs neither measurement as an input, because its arithmetic instead uses the recorded embryo age. An ultrasound comparison is clinical evidence for the treating team, separate from this transfer-date subtraction.
University of Cincinnati: ultrasound criteria for pregnancy dating, revised May 5, 2015Clinical Estimates calculators: Period Calculator, GFR Calculator, BAC Calculator, Creatinine Clearance Calculator, Ovulation Calculator, Pregnancy Week Calculator.
With IVF, the day of conception is known, so the date counts from the transfer and not from a last period. A day 5 embryo transferred on June 1 is dated 19 days into the pregnancy that day. The due date follows 261 days later, which is 266 minus the 5 days the embryo had already lived.
A day 3 embryo pushes the date two days later, since it is two days younger.
Embryo age is measured on the transfer date. The day 3 and day 5 offsets differ by two days; they describe different stages at transfer.
See the regular calculation on the due date calculator, and the pregnancy week and conception date pages for other dating. The pregnancy weight gain and ovulation pages cover related planning. Clinic dating and ultrasound assessment can differ from a transfer-date arithmetic estimate.
How is an IVF due date calculated?
From the embryo transfer date, adding 266 days minus the embryo's age in days, since the transfer date gives precise timing.
Why is IVF dating more accurate?
Because the date of fertilization and the embryo's age are known, unlike a natural pregnancy where ovulation timing is estimated.
What does gestational age on transfer day mean?
It is the equivalent pregnancy age in days counted from a hypothetical last period, so transfer of a five-day embryo is 19 days of gestational age.