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IVF due date calculator
Enter your embryo transfer date and choose a day 3 or day 5 transfer to see the estimated due date, how many weeks pregnant you are today and the main pregnancy milestones.
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How it works
Enter the transfer dateThe day the embryo was transferred.
Choose the embryo ageDay 3 or day 5 (blastocyst) transfer.
Read your datesSee the due date, today's week and the milestones.
Due date after an embryo transfer
With IVF the age of the embryo is known exactly, so the due date is usually more precise than one based on a period. Pregnancy weeks are still counted the usual way, as if from a last period two weeks before fertilization. A day 5 embryo (blastocyst) transferred on a given day matches a pregnancy of 2 weeks 5 days on that day, so the due date is 261 days after the transfer. A day 3 embryo matches 2 weeks 3 days, which gives 263 days.
For example, a day 5 transfer on 10 March 2026 gives a due date of 26 November 2026. A frozen embryo transfer is counted in the same way: what matters is the age of the embryo when it was transferred, not when it was frozen.
After the transfer
Clinics usually check a blood pregnancy test about 9 to 11 days after the transfer, which is around 4 weeks of pregnancy. The milestone list shows that week and the following ones, such as the start of the second trimester and the mid-pregnancy scan window. Your clinic may give a slightly different date depending on its own convention.
Frequently asked questions
How do I count a day 6 blastocyst?
Choose day 5 and enter the transfer date one day earlier, or simply subtract one day from the result. The difference is one day.
How accurate is the due date?
It is an estimate. Most babies are born within two weeks either side of it, and an early ultrasound can correct it by a few days.
My cycle is irregular. What should I enter?
Use your usual average cycle length. With very irregular cycles the date from your last period is less reliable, and an ultrasound will give a better estimate.
Why am I two weeks pregnant at conception?
Pregnancy weeks are counted from the first day of the last period, about two weeks before ovulation, because that day is easier to know than the day of conception.
Are my dates saved or sent anywhere?
No. The calculation runs in your browser, the dates are not saved and are not added to the share link. The calculator is free and needs no account.
Does this replace a check with my doctor?
No. It uses standard formulas to give an estimate. Your midwife or doctor confirms the due date and follows the pregnancy.