π€° IVF Due Date Calculator
Precise dating from your IVF milestone.
For informational purposes only, not medical advice. Consult a healthcare professional.
IVF dating is more precise than dating by last period because the embryo's exact age is known. Standard pregnancy math counts 280 days from the last menstrual period, which assumes ovulation on day 14. In IVF, you simply subtract the embryo's age from 280: a day-5 blastocyst is already 19 days into that count (14 + 5), so the due date is transfer day plus 261 days.
Enter your procedure date and type: egg retrieval, day-3 transfer, or day-5/day-6 blastocyst transfer. The calculator returns the due date, the equivalent LMP for talking with providers who chart by LMP, and trimester start dates.
How to Use This Calculator
Pick the date of your egg retrieval or embryo transfer and select which procedure it was. For frozen transfers, use the transfer date and the embryo's age at freezing (day 3 or day 5/6). Read the due date and the equivalent LMP. Early ultrasound may adjust dating by a few days; that is normal.
Enter the date of the retrieval or transfer.
Select the procedure type so the embryo's age is subtracted correctly.
Read the due date and the equivalent LMP date.
Note the trimester start dates for planning.
The Subtraction Behind IVF Dating
Day-3 transfer: +263 days (280 - 17)
Day-5 transfer: +261 days (280 - 19)
Obstetric dating counts gestational age from the first day of the last period, adding two pre-conception weeks to the embryo's true age. Ovulation and fertilization are treated as day 14. An egg retrieved on day 14 is therefore already "2 weeks pregnant" in obstetric terms, so the due date is retrieval plus 266 days (38 weeks). A day-3 embryo transferred on day 17 gets 263 days; a day-5 blastocyst transferred on day 19 gets 261. The arithmetic is exact because, unlike natural conception, nobody is guessing when ovulation happened.
Worked Example
A day-5 blastocyst transfer on Sep 20, 2026 gives a due date of Jun 8, 2027: 261 days from transfer day. The equivalent LMP is Equivalent LMP: Sep 1, 2026, which is what ultrasound dating will roughly confirm. A day-3 transfer on the same date would add 263 days instead, landing two days later.
What the Dates Tell You
The due date is an estimate: only about 1 in 20 babies arrives on it, with most coming within two weeks either side. The equivalent LMP exists because prenatal records, screening windows, and ultrasound reports all speak LMP; handing your provider the IVF-derived LMP keeps everyone on the same page. If a first-trimester ultrasound disagrees by more than about 5 to 7 days, clinicians usually redate by the ultrasound, since crown-rump length is very accurate early on.
Your Clinic Owns the Dating
Use this for planning and for understanding your chart, but let your fertility clinic and OB confirm the official dates: they may adjust for exactly when the embryo was frozen or for ultrasound findings. Any bleeding, severe pain, or concerning symptoms in early pregnancy warrant a prompt call regardless of what the dates say. For informational purposes only, not medical advice. Consult a healthcare professional.
Related tools: pregnancy due date calculator, implantation calculator and mean sac diameter dating.
For informational purposes only, not medical advice. Consult a healthcare professional.
Frequently Asked Questions
How is an IVF due date calculated?
By embryo age: subtract it from the standard 280-day gestation. Egg retrieval adds 266 days, day-3 transfer 263, day-5 blastocyst 261.
Is IVF dating more accurate than LMP dating?
Yes. The embryo's exact age is known, so there is no guessing about ovulation day as there is with natural conception.
What is my gestational age on transfer day?
On day-5 transfer day you are 2 weeks and 5 days pregnant in obstetric terms. The two weeks before retrieval count toward gestational age.
Does a frozen transfer change the math?
No. Use the transfer date and the embryo's age when frozen: a frozen day-5 blastocyst uses the same 261-day addition.
Why did my ultrasound change my due date?
First-trimester crown-rump length measures the embryo directly and can differ by a few days from transfer math. Clinicians usually trust the ultrasound if the gap exceeds about 5 days.
When do trimesters start in IVF pregnancy?
Same as any pregnancy by gestational age: second trimester around 13 weeks 6 days to 14 weeks, third around 27 to 28 weeks from the equivalent LMP.
Can the due date change with twins?
The dating math is identical. Twin pregnancies are simply monitored more closely and often deliver earlier, which is separate from the due date itself.
What if I had a day-6 transfer?
Subtract one more day: add 260 days instead of 261. The calculator includes day-6 as an option.