If your clinic transferred your embryo on day 3, day 5 or day 6, your due date shifts by a few days, and those few days confuse almost everyone. This guide compares the ivf due date day 3 vs day 5 vs day 6 methods side by side, so you can work out your own date in about a minute.
The method is the same in all three cases. Only one number changes: how many days you add to your transfer date.
The Short Answer
| Embryo transfer day | Days to add to your transfer date | Your pregnancy age on transfer day |
|---|---|---|
| Day 3 transfer | 263 days | 2 weeks and 3 days |
| Day 5 transfer | 261 days | 2 weeks and 5 days |
| Day 6 transfer | 260 days | 2 weeks and 6 days |
So, for the same transfer date, a day 6 transfer gives the earliest due date and a day 3 transfer gives the latest one. The gap between them is only three days.
Why the Transfer Day Changes the Due Date
A normal pregnancy is counted from the first day of the last period, which is about two weeks before conception. An IVF pregnancy follows the same counting, so the embryo’s age is first turned into pregnancy weeks by adding 14 days.
That is why a day 5 embryo is already 2 weeks and 5 days “pregnant” on transfer day (14 + 5 = 19 days). A full pregnancy lasts 266 days from conception. So the days left are 266 minus the embryo’s age:
- Day 3 embryo: 266 − 3 = 263 days left
- Day 5 embryo: 266 − 5 = 261 days left
- Day 6 embryo: 266 − 6 = 260 days left
In short, an older embryo has already finished more of the 266 days in the lab, so fewer days remain after the transfer.
How to Calculate Your IVF Due Date
- First, find your embryo transfer date. It is on your clinic’s transfer report.
- Next, check the embryo’s day on that report: day 3, day 5 or day 6.
- Then add the matching number of days from the table above: 263, 261 or 260.
- Or skip the counting and use our IVF Due Date Calculator, which does this maths for you and also shows your current pregnancy week.
Worked Example: All Three Transfers on 1 March 2026
To see the difference clearly, imagine all three transfers happen on the same day, 1 March 2026:
| Transfer date | Embryo day | Days added | Due date |
|---|---|---|---|
| 1 March 2026 | Day 3 | 263 days | 19 November 2026 |
| 1 March 2026 | Day 5 | 261 days | 17 November 2026 |
| 1 March 2026 | Day 6 | 260 days | 16 November 2026 |
Notice the pattern: the day 3 transfer gives the latest due date, because that embryo was the youngest on transfer day. It still needs the most growing time inside the womb.
Does a Day 6 Transfer Mean the Embryo Is Behind?
No. A day 6 embryo has reached the same blastocyst stage as a day 5 embryo; it simply reached that stage a little more slowly in the lab. The counting method already allows for this, which is why a day 6 transfer gets one day less added than a day 5 transfer.
Because of this, you should not “correct” a day 6 due date by adding an extra day yourself. Your clinic’s date already follows this same method.
Fresh vs Frozen Transfers: Does Anything Change?
The method stays the same for a frozen embryo transfer. What matters is the embryo’s age, which is the day it reached before freezing, plus your actual transfer date.
For example, a day 5 embryo that was frozen and transferred two months later is still counted as a day 5 embryo. You still add 261 days to the transfer date. Freezing pauses the embryo’s age; it does not reset it.
Will My Ultrasound Change This Due Date?
For IVF pregnancies, the date worked out from the transfer is considered the most accurate one. The American College of Obstetricians and Gynecologists (ACOG) advises that when a pregnancy is conceived with assisted reproductive technology, the ART-based due date should be used and should not normally be changed, even if an early ultrasound suggests a slightly different date.
So if your scan date differs from your transfer-based date by a few days, do not worry. Your clinic will almost always keep the transfer-based date.
Frequently Asked Questions
Which transfer day gives the earliest due date?
For the same transfer date, a day 6 transfer gives the earliest due date, because the fewest days (260) are added. A day 3 transfer gives the latest due date, three days after the day 6 date.
My clinic’s due date is one or two days different from mine. Why?
Clinics sometimes count the transfer day itself as day one, or use a slightly different counting method. A difference of one or two days is common and harmless. Always follow your clinic’s date, because your appointments and tests are planned around it.
Is a day 5 transfer better than a day 3 transfer?
That is a question about embryo development and success rates, not about dates. Day 3 embryos are transferred at the cleavage stage and day 5 or 6 embryos at the blastocyst stage, and clinics choose the day based on how your embryos are growing. Whichever day your clinic chose, the due date method in this guide is the same.
Do twins change the IVF due date calculation?
No. The due date is worked out in exactly the same way for twins. Your clinic may plan a somewhat earlier delivery for a twin pregnancy, but the official due date itself does not change.
Can I use a normal due date calculator for IVF?
A normal calculator works from your last period, which does not match an IVF cycle. Use the transfer-based method in this guide, or our IVF Due Date Calculator, for an accurate date.
Related Tools
- IVF Due Date Calculator — works out your due date from your embryo transfer date
- Due Date Calculator — finds your due date from your last period
- hCG Calculator — checks how fast your hCG level is rising
- Pregnancy Weight Gain Calculator — shows the healthy weight gain range for your pregnancy
- Ultrasound Due Date Calculator — works out your due date from an ultrasound scan date
Sources
American College of Obstetricians and Gynecologists (ACOG), Committee Opinion No. 700: Methods for Estimating the Due Date — for IVF pregnancies, the due date based on the embryo transfer is used. Transfer-day additions (263, 261 and 260 days) follow the standard rule of 266 days from conception minus the embryo’s age in days.