How do I calculate my due date after a 5-day blastocyst transfer?

Add 261 days to your transfer date. The general IVF formula is: due date = transfer date + (266 - embryo age in days). For a day-5 blastocyst, 266 - 5 = 261. Example: a transfer on 1 January 2026 gives an estimated due date of 19 September 2026.

Does a frozen embryo transfer (FET) change the due date calculation?

No. Fresh and frozen transfers use exactly the same math - only the embryo's age at transfer matters, not how long it was frozen. A frozen day-5 blastocyst transferred on 10 June 2026 has the same due date as a fresh day-5 transfer on that date: transfer date + 261 days.

What is the difference between a 3-day, 5-day and 6-day transfer due date?

Day-3 (cleavage stage): transfer date + 263 days. Day-5 (blastocyst): transfer date + 261 days. Day-6 (blastocyst): transfer date + 260 days. Each extra day the embryo developed in the lab is one day less to add, because full gestation is counted as 266 days from fertilization.

Can I calculate my IVF due date from the egg retrieval date?

Yes. Add 266 days (38 weeks) to your egg retrieval date. Retrieval day is treated as the fertilization date, so this is the most direct IVF formula. It is fully consistent with the transfer-date formula: a day-5 transfer happens 5 days after retrieval, and (retrieval + 266) equals (transfer + 261).

Why can't I use a regular pregnancy due date calculator for IVF?

Standard calculators use Naegele's rule from your last menstrual period (LMP), which assumes ovulation on day 14 of a natural cycle. In IVF the cycle is medically controlled, so LMP-based dating is unreliable. IVF due dates are calculated from the known retrieval or transfer date instead, which is more precise. Our general pregnancy due date calculator covers LMP-based dating for natural conception; this tool is dedicated to IVF and frozen embryo transfers.

How many weeks pregnant am I on embryo transfer day?

On transfer day you are already counted as 2 weeks and 3 days (day-3 transfer), 2 weeks and 5 days (day-5 transfer), or 2 weeks and 6 days (day-6 transfer) pregnant. Obstetric dating counts from an 'equivalent LMP' set 14 days before egg retrieval, so the embryo's lab days are included.

What if my embryo was transferred on day 2, day 4, or another age?

The formula generalizes: due date = transfer date + (266 - embryo age). So a day-2 transfer adds 264 days and a day-4 transfer adds 262 days. This calculator supports any embryo age from 1 to 7 days.

How is the due date calculated for donor egg IVF?

Count 266 days from the donor's egg retrieval date - the same as using your own eggs. The identity of the egg provider does not change the math; only the fertilization (retrieval) date matters.

How accurate is an IVF due date?

IVF due dates are the most precisely dated of any pregnancy method because fertilization and transfer dates are documented. Even so, a due date is an estimate: only about 5% of babies are born on the exact date, and a normal delivery can occur anywhere from 37 to 42 weeks. Always confirm dating with your obstetrician and early ultrasound.

Does the calculation change for twins or multiples?

No - the due-date math is identical for singleton and multiple pregnancies. What differs is medical management: twin pregnancies are often delivered earlier, typically around 37-38 weeks, as decided by your doctor. This calculator gives the standard 40-week estimate; your clinic sets the actual delivery plan.

What is my 'equivalent LMP' and why does my clinic ask for it?

Your equivalent LMP is your estimated due date minus 280 days (equivalently, egg retrieval minus 14 days). Clinics convert IVF dates to an LMP-equivalent so all prenatal care, screenings, and milestone charts follow the standard gestational-age framework used for every pregnancy.

Is a day-6 blastocyst due date different from day-5?

Yes, by one day. A day-6 blastocyst is one day older at transfer, so you add 260 days instead of 261: due date = transfer date + (266 - 6). Some clinics transfer on day 6 or day 7 when embryos need extra development time; the formula handles any age.

IVF Due Date Calculator — EDD by Transfer, Retrieval & FET Date

Calculate your IVF due date

Embryo transfer date The day your embryo was placed in the uterus.

Embryo age at transfer Most common: day 5 (blastocyst). Unsure? Check your clinic paperwork — day 5 is the modern standard.

Other embryo age (1–7 days, optional)

Calculate “how far along” as of Defaults to today. Change it to see gestational age on any date.

Your results

Estimated due date

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You are

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Trimester

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Fertilization (conception)

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Equivalent LMP

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Gestational age at transfer

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Days to go

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Remember: this is an educational estimate, not medical advice. About 5% of babies arrive on the exact due date; a normal delivery happens between 37 and 42 weeks. Confirm your official due date with your clinic.

Pregnancy milestones

How IVF due dates are calculated

Natural pregnancies are dated from the last menstrual period (LMP) because the exact fertilization day is unknown. In IVF the timeline is documented, so dating starts from a known point instead. Full gestation is counted as 266 days (38 weeks) from fertilization.

Due date = transfer date + (266 − embryo age in days)
Day 3 → +263 days • Day 5 → +261 days • Day 6 → +260 days
Due date = egg retrieval date + 266 days

Both formulas always agree: a day-5 transfer happens 5 days after retrieval, so retrieval + 266 is exactly transfer + 261. Your clinic converts these dates to an equivalent LMP (retrieval minus 14 days) so every screening and milestone chart uses the standard 40-week framework — which is why you are already “2 weeks 5 days pregnant” on the day of a day-5 transfer.

IVF vs. natural conception: this tool is dedicated to IVF and frozen embryo transfers (dates you know exactly). For naturally conceived pregnancies dated from your last period, use our pregnancy due date calculator (Naegele’s rule, conception date, or ultrasound dating).

Educational estimate only: these formulas produce the standard obstetric estimate (266 days from fertilization). Your clinic may adjust dating after early ultrasound — always confirm your official due date with your fertility clinic or obstetrician.

IVF Due Date Calculator

Calculate your IVF due date

Your results

Pregnancy milestones

How IVF due dates are calculated

Frequently asked questions

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