IVF due date calculator: due date from your embryo transfer
Estimated due date: Thursday, June 24, 2027
Transfer date + 261 days (266 days from fertilisation, minus the 5 days your embryo had already grown). Your clinic will confirm it with an early scan.
🔒 Calculated in your browser. Nothing you type is sent or stored. Estimates only: bodies vary.
An IVF due date calculator counts 266 days from fertilization, minus the days your embryo had already grown before transfer. So the due date is your transfer date + 261 days for a day 5 blastocyst, + 263 days for a day 3 embryo and + 260 days for a day 6 blastocyst. Your clinic confirms the date at your early scan.
How the IVF due date calculator works
With IVF you know something most pregnancies never do: the exact age of the embryo. That makes an IVF due date the most precise of all. ACOG advises that pregnancies from assisted reproduction should be dated from the embryo age and transfer date, rather than from a last period.
- Enter your embryo transfer date (fresh or frozen, the maths is the same).
- Pick the embryo's age on the day it was transferred: day 3, day 5 or day 6.
- Read your estimated due date. The calculator shows the number of days it added.
The formula
Due date = transfer date + (266 − embryo age in days). 266 days is the average time from fertilization (egg retrieval day) to birth. Your embryo had already been growing for 3, 5 or 6 of those days in the lab, so they're taken off.
| Embryo at transfer | Days added to transfer date | Equivalent "last period" date |
|---|---|---|
| Day 3 embryo | 263 days | transfer date − 17 days |
| Day 5 blastocyst | 261 days | transfer date − 19 days |
| Day 6 blastocyst | 260 days | transfer date − 20 days |
The "equivalent last period" date is how your clinic and maternity team will count your weeks, so you'll be called 2 weeks pregnant on egg retrieval day, just like a natural pregnancy.
A worked example: 5 day transfer due date
Your day 5 blastocyst was transferred on April 2. April 2 + 261 days = December 19. Your equivalent LMP is March 14, so on transfer day you're counted as 2 weeks 5 days pregnant, and at your beta test 9 to 11 days later you'd be around 4 weeks.
| Transfer on April 2 | Estimated due date |
|---|---|
| Day 3 embryo | December 21 |
| Day 5 blastocyst | December 19 |
| Day 6 blastocyst | December 18 |
For a frozen transfer, use the transfer date and the age the embryo was when it was frozen (usually day 5 or 6). The time spent frozen doesn't count. Calculated in your browser, nothing stored.
How accurate is an IVF due date?
As accurate as a due date gets, since the conception date is known. Even so, the due date is the middle of a range. Most babies arrive between 37 and 42 weeks, and twins (more common after IVF, especially with two embryos transferred) usually arrive earlier. Your clinic will check the pregnancy with an early ultrasound, usually around 6 to 7 weeks, and your maternity team uses the IVF-based date from then on.
Your beta hCG and early weeks
Most clinics schedule a blood test (beta hCG) about 9 to 11 days after a day 5 transfer, a little later after a day 3 transfer. Home tests can be misleading if you had an hCG trigger shot, since it can stay in your system for up to about two weeks. If your clinic repeats the test, our hCG doubling time calculator shows the rise between results, but your clinic interprets the numbers, alongside your scan.
The wait between transfer and beta can be one of the hardest parts of treatment. Progesterone support can also bring mood changes, tiredness and breast tenderness that look a lot like PMS, which makes the wait harder to read. Plan small comforts, and lean on people you trust.
Call your clinic or get urgent care for heavy bleeding, severe or one-sided pelvic pain, shoulder-tip pain, fainting, or, after egg retrieval, a fast-swelling tummy, shortness of breath or passing very little urine (possible ovarian hyperstimulation).
Frequently asked questions
How do you calculate a due date after a 5 day transfer?
Add 261 days to the transfer date. A day 5 transfer on January 10 gives a due date of September 28.
How do you calculate a due date after a 3 day transfer?
Add 263 days to the transfer date. That's 266 days from fertilization, minus the 3 days the embryo grew in the lab.
Is the IVF due date different for a frozen transfer?
No. Use the transfer date and the embryo's age when it was frozen. Time in storage doesn't count.
How many weeks pregnant am I on transfer day?
About 2 weeks 3 days for a day 3 embryo, and 2 weeks 5 days for a day 5 blastocyst, because pregnancy is counted from an equivalent last period two weeks before fertilization.
Sources
- ACOG Committee Opinion 700: Methods for Estimating the Due Date
- HFEA: In vitro fertilisation (IVF)
- NHS: IVF
This page is for information only and isn’t medical advice. If something worries you, please talk to a doctor.
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