IVF Due Date Calculator
Enter your embryo transfer date and select the transfer type to get your estimated due date (EDD), trimester start and end dates, current gestational age, and a week-by-week milestone timeline. This calculator handles day-3 cleavage transfers, day-5 and day-6 blastocysts, and frozen embryo transfers (FET). Results update as you type.
How IVF due dates are calculated
A natural pregnancy is dated from the last menstrual period (LMP), adding 280 days to get the estimated due date. IVF pregnancies skip the guesswork: because the embryo age is known precisely on the day of transfer, the calculation is more accurate. For a day-5 blastocyst, 261 days are added to the transfer date (266 days from fertilization minus the 5 days the embryo already spent in the lab). A day-3 cleavage embryo gets 263 days added, and an embryo transferred on the same day as egg retrieval (day 0) gets the full 266 days. This produces a gestational-age-adjusted due date that aligns with standard 40-week obstetric dating.
Fresh vs. frozen embryo transfer (FET)
The due date formula is the same whether the embryo was transferred fresh (days after egg retrieval in the same cycle) or frozen and thawed later. What matters is the embryo's age in days at the time of transfer - not the date the embryo was frozen. A day-5 frozen blastocyst transferred on any date adds exactly 261 days to reach the EDD, just as a fresh day-5 blastocyst does. Clinics sometimes note transfer date, retrieval date, and fertilization date separately; use the actual transfer date with this calculator.
Gestational age vs. fetal age in IVF
Gestational age is counted from a fictional LMP-equivalent date, which is calculated by subtracting 280 days from your EDD. This keeps IVF pregnancies comparable to naturally conceived ones in medical records and on growth charts. Fetal age (also called embryo or post-fertilization age) is 2 weeks less than gestational age. Most doctors, apps, and pregnancy books use gestational age, so the week numbers shown in this calculator match what your OB-GYN will use. For example, a day-5 transfer counts as approximately 2 weeks and 5 days of gestational age on the day of transfer.
When your due date may change
An estimated due date from this calculator is a starting point, not a guarantee. Your OB-GYN or reproductive endocrinologist will typically confirm the date with a transvaginal ultrasound at 6-10 weeks, which measures the fetal crown-rump length (CRL). If the CRL measurement puts the embryo more than 5-7 days ahead of or behind the calculator's date, clinicians will often revise the EDD to match the ultrasound. Only about 5 percent of babies arrive on their exact due date; 90 percent are born within 2 weeks either side. Full term is considered 37-42 weeks of gestation.
IVF due date calculation methods
| Transfer Type | Days Added | Rationale |
|---|---|---|
| Day-5 blastocyst (most common) | 261 | 266 - 5 days of development |
| Day-6 blastocyst | 260 | 266 - 6 days of development |
| Day-3 cleavage embryo | 263 | 266 - 3 days of development |
| Egg retrieval date (day 0) | 266 | No days of development elapsed yet |
| LMP date (natural / IUI) | 280 | Standard Naegele rule (38 weeks from conception + 2 weeks) |
Days added to the transfer date (or retrieval date) to reach your estimated due date. Based on a 266-day fertilization-to-birth timeline.
Frequently asked questions
Is my IVF due date calculated the same way as a natural pregnancy?
Almost, but with more precision. A natural pregnancy adds 280 days to the last menstrual period (LMP). An IVF due date subtracts the embryo's age at transfer from 266 days and adds that number to the transfer date. The result aligns with standard 40-week pregnancy dating, so your due date is expressed in the same gestational weeks your doctor uses.
What is the difference between a day-3 and day-5 transfer?
Embryos are cultured in the lab for either 3 days (cleavage stage) or 5 days (blastocyst stage) before being placed in the uterus. Because a day-5 embryo has been developing in the lab for 2 extra days, 2 fewer days are added to the transfer date when calculating the due date (261 days for day 5 vs. 263 days for day 3). Day-5 blastocyst transfers are now the most common approach because they allow better embryo selection.
Can I use this calculator for a frozen embryo transfer (FET)?
Yes. The embryo's age at the time of transfer is what matters, not whether it was fresh or frozen. A frozen day-5 blastocyst adds 261 days to the transfer date, exactly the same as a fresh day-5 transfer. Enter the date the embryo was placed in the uterus - not the original retrieval or freeze date.
When will I know my gestational age?
Enter today's date in the "Today's date" field and the calculator will show your current gestational age in weeks and days. This is counted from the LMP-equivalent date (your EDD minus 280 days), keeping your chart consistent with standard obstetric numbering. On the day of a day-5 transfer, for example, you are typically at 2 weeks and 5 days of gestational age.
Can a due date calculated from IVF transfer be wrong?
IVF dating is generally more accurate than LMP-based dating because the embryo's age is known precisely. However, the due date is still an estimate. An early ultrasound measuring the crown-rump length (CRL) is the most accurate way to confirm dating, and if the scan measurement disagrees with the calculator by more than about 5-7 days, your provider may adjust the EDD accordingly.
How many weeks pregnant am I after a day-5 transfer?
On the day of a day-5 blastocyst transfer you are 2 weeks and 5 days (2w5d) pregnant by gestational age, because the embryo has been alive for 5 days and the LMP-equivalent is set 14 days before fertilization by convention. Most IVF patients have their first beta HCG blood test at about 9-11 days after a day-5 transfer, which corresponds to roughly 3 weeks and 4 days of gestational age.