FET Due Date Calculator

About FET Pregnancy Dating

A frozen embryo transfer (FET) is one of the most common assisted reproductive procedures today. As embryo freezing technology (vitrification) has improved dramatically, FET success rates now match or exceed fresh IVF cycles. Calculating your FET due date uses exactly the same formula as fresh IVF: Due Date = Transfer Date + (266 − Embryo Age).

The key insight is that freezing pauses — not resets — the embryo’s developmental clock. Whether your embryo was frozen on Day 5 in 2022 and transferred in 2024, it is still a 5-day-old blastocyst at transfer. This consistent developmental age is what makes FET due date calculation so straightforward and reliable.

FET Protocol and Timing

FET cycles can be performed on natural cycles (monitoring your own ovulation) or medicated cycles (using estrogen and progesterone to prepare the uterine lining on a controlled schedule). Medicated FET cycles give the clinic more precise control over the transfer timing. In a typical medicated FET, estrogen is started around day 2 of your cycle, lining thickness is checked by ultrasound around day 12–14, progesterone supplementation begins, and transfer occurs 5 days after starting progesterone for a blastocyst.

What to Expect After a Positive FET

After a positive beta hCG, most RE clinics monitor you for 8–10 weeks before releasing you to an OB. You’ll continue progesterone supplementation (usually until week 8–12) and have regular beta and ultrasound monitoring. Your FET due date calculated here provides an accurate starting point for your pregnancy timeline. The full ResultDashboard below shows your milestones, baby development week by week, and planning dates.