Calculate an IVF transfer-based due date from embryo transfer date and embryo age, then review gestational age, gestational age at transfer, equivalent LMP.
Health estimate
Topic review: Sarah Johansson
Maternal Health Writer. Assigned as the health topic reviewer for pregnancy, fertility, ovulation, and women’s health calculators.
IVF due date planning Use the embryo transfer date and embryo age at transfer to estimate a transfer-based due date, equivalent LMP, and milestone dates for early pregnancy planning.
Transfer timing
IVF dating uses the embryo transfer date plus embryo age at transfer. Fresh and frozen transfers use the same date arithmetic; the key difference is whether the embryo was transferred on day 3 or day 5.
Embryo age at transfer
Clinical confirmation still matters IVF date math is usually more precise than natural-conception dating, but clinics can still refine the official estimated due date after ultrasound review. Treat this as a planning estimate, not the final obstetric record.
Transfer-based due date
January 24, 2027
247 days until the transfer-based due date
4w 5d
Current gestational age
2w 5d
Gestational age at transfer
247 days
Relative to due date
35w
Weeks remaining
First trimester
Trimester
IVF day-5 blastocyst transfer
Dating basis
IVF timeline details
Milestone
Date
Why it matters
Embryo transfer
May 8, 2026
Day 5 (blastocyst) transfer date used as the IVF dating anchor.
Equivalent conception
May 3, 2026
Back-calculated day-0 conception date based on embryo age at transfer.
Equivalent LMP
April 19, 2026
Pregnancy weeks are counted from this equivalent last-period date.
Estimated due date
January 24, 2027
Transfer-based estimated due date before scan-based adjustment.
Pregnancy milestones
Milestone
Date
Planning note
7-week scan point
June 7, 2026
Common fertility-clinic ultrasound timing for heartbeat and early growth review.
12-week dating scan point
July 12, 2026
Typical NHS dating-scan milestone when the pregnancy timeline is formally reviewed.
20-week anatomy scan point
September 6, 2026
The mid-pregnancy scan milestone often used for structural review.
37-week term window start
January 3, 2027
Pregnancy enters the early-term window from this point onward.
How to use this estimate Use the transfer-based date for planning and conversation with your clinic, but follow the official estimated due date your fertility team or obstetric team confirms after ultrasound review.
In IVF, the embryo transfer date is a precise known point in conception history — unlike natural conception. The age of the embryo at transfer (day 3, day 5, or day 6) determines how many days before the equivalent "conception" the transfer occurred, which in turn sets the estimated due date, gestational age, and the weeks-pregnant result people usually search for.
How IVF due dates are calculated
For a day-5 (blastocyst) transfer, the EDD is transfer date + 261 days. For a day-3 (cleavage-stage) transfer, the EDD is transfer date + 263 days. For a day-6 blastocyst transfer, the EDD is transfer date + 260 days. This reflects the standard convention that conception occurred on the day of egg retrieval (day 0), and the EDD is 266 days from conception.
The equivalent LMP is EDD minus 280 days — the same Naegele's rule basis used in natural conception. Gestational age is then counted from this equivalent LMP.
EDD (day-5) = transfer date + 261 days
Blastocyst transfer This is the specific relationship the calculator applies when building the result.
EDD (day-3) = transfer date + 263 days
Cleavage-stage transfer This is the specific relationship the calculator applies when building the result.
EDD (day-6) = transfer date + 260 days
Expanded blastocyst transfer This is the specific relationship the calculator applies when building the result.
What the transfer age means for weeks pregnant
At the moment of transfer, you are already several days pregnant on the standard obstetric calendar because IVF dating still uses the same 40-week framework as natural conception. A day-3 transfer corresponds to 2 weeks 3 days, a day-5 transfer to 2 weeks 5 days, and a day-6 transfer to 2 weeks 6 days.
That is why IVF searches often ask how many weeks pregnant you are at transfer or why the calculator should show gestational age right away. The answer is not that pregnancy starts on transfer day; it is that the fertility timeline is being translated into the same gestational clock used by midwives and obstetricians.
Worked example: day-5 embryo transfer
If a day-5 embryo transfer happened on 1 January 2026, the transfer-based due date is 19 September 2026. The equivalent conception date is 27 December 2025, and the equivalent last menstrual period is 13 December 2025.
That gives you the same pregnancy-week counting system used on standard due-date pages, but anchored to the known IVF transfer timeline rather than an uncertain ovulation date. It also makes milestone planning easier, because the 7-week scan point, 12-week dating scan point, and 20-week anatomy scan point can all be back-calculated from the same IVF timeline.
Confirming gestational age by ultrasound
While the mathematical EDD from transfer date is precise, most fertility clinics also confirm gestational age by crown-rump length (CRL) at the 7–8 week scan. If the CRL measurement differs significantly from the transfer-based gestational age, the ultrasound date takes precedence in some clinical settings.
After graduation from the fertility clinic, your obstetric team will set the official EDD — usually confirmed at the 12-week dating scan.
Fresh, frozen, and donor-egg cycles
Fresh and frozen embryo transfers use the same date logic. What changes the calculation is the embryo's age at transfer, not whether it was frozen beforehand. That is why searches such as IVF due date calculator day 5 transfer and frozen embryo transfer due date usually point to the same planning approach.
Donor-egg cycles still use the transfer date and embryo age for the pregnancy timeline. The donor egg can change treatment context, but it does not change the basic transfer-based date math on this page.
The calculator keeps the arithmetic visible so the 260-day, 261-day, and 263-day offsets are easy to audit. That makes it simpler to compare the clinic estimate, your own calendar, and any later scan-based adjustment without reverse-engineering the date yourself.
What comes after the transfer date
Fertility clinics usually schedule a beta hCG blood test and then an early scan if the pregnancy continues to develop as expected. The exact timing can vary by clinic, but the calculator's milestone rows help you see where those checkpoints sit relative to the transfer-based due date.
If your scan results redates the pregnancy, use the clinic's estimate rather than the calculator result. The calculator is best used for planning, note-taking, and understanding how the IVF timeline maps onto standard pregnancy dating.
Frequently asked questions
Does embryo freezing (FET) change the calculation?
No — the calculation uses the transfer date regardless of whether the embryo is fresh or frozen. What matters for the due date is when the embryo was placed in the uterus and its age at that point.
Why is my IVF due date different from the dating scan?
Embryo growth rates vary. If CRL measurements indicate a slightly different gestational age at the first scan, your fertility specialist or midwife may adjust the EDD accordingly. Minor discrepancies of 3–5 days are common.
Why are day-3 and day-5 transfers calculated differently?
A day-5 blastocyst is already two days older than a day-3 embryo at transfer, so the estimated due date starts two days earlier in the IVF calculation. The calculator adjusts for that difference so the gestational age matches the embryo's actual development stage.
Can my IVF due date change after the first scan?
Yes. The transfer-based date is a planning estimate, but first-trimester crown-rump length measurements can lead your clinic to refine the official EDD if the scan result and transfer-based date do not line up closely.
Does a frozen embryo transfer use the same due-date logic as a fresh transfer?
Yes. The calculation still starts from the transfer date and the embryo's age at transfer. Whether the embryo was frozen beforehand does not change the basic dating math.
Why does a day-5 transfer have a different offset from a day-3 transfer?
Because the embryo is transferred at a different developmental stage. A day-5 blastocyst is two days older than a day-3 embryo at transfer, so the estimated due date is adjusted accordingly.
Does a day-6 transfer use the same calculator?
Yes. A day-6 blastocyst transfer uses the same transfer-based logic with a 260-day offset, because the embryo is one day older at transfer than a day-5 blastocyst and three days older than a day-3 cleavage-stage embryo.
How many weeks pregnant am I at IVF transfer?
A day-3 transfer corresponds to 2 weeks 3 days pregnant, a day-5 transfer to 2 weeks 5 days, and a day-6 transfer to 2 weeks 6 days on the standard gestational calendar. That is why IVF calculators often show gestational age immediately after transfer.
Can my due date change after the first IVF scan?
Yes. If the early ultrasound measurement differs meaningfully from the transfer-based estimate, your clinic may redate the pregnancy. That is common when crown-rump length measurements suggest a slightly different gestational age.
Does donor-egg IVF change the due date formula?
No. The due date still comes from the transfer date and embryo age at transfer. Donor eggs change the treatment context, but they do not change the basic transfer-based pregnancy dating formula used here.
When is the first scan after IVF usually done?
Clinics often schedule an early scan around 7 to 8 weeks of gestation, but exact timing varies by clinic and individual circumstances. The milestone rows on this page show where that window sits relative to the transfer-based due date.
