IVF due date calculator

With IVF you know exactly when the embryo was created and transferred, so the due date doesn't depend on a period or a guess about ovulation. ACOG Committee Opinion 700 gives the rule:

Due date = transfer date + 266 days − embryo age in days

The 266 days is the length of pregnancy from conception (38 weeks). Subtracting the embryo's age accounts for the days it had already grown in the lab.

What you enter	Days added to the date
Day 3 embryo transfer	+263
Day 5 (blastocyst) transfer	+261
Day 6 blastocyst transfer	+260
Egg retrieval or IUI date	+266

For egg retrieval or IUI, the calculator treats that date as the conception date. Behind the scenes, every option is converted to an LMP-equivalent date (the day your last period would have started in a natural cycle), so your weeks and days match the way your provider counts them.

Say your transfer was on 03/03/2026.

Day 5 blastocyst:

• Due date: 03/03/2026 + 261 days = 11/19/2026
• LMP-equivalent date: 03/03/2026 − 5 − 14 days = 02/12/2026
• On transfer day you were already 2 weeks 5 days pregnant
• You reach 4 weeks, roughly when a period would have been due, on 03/12/2026

Day 3 embryo, same transfer date:

• Due date: 03/03/2026 + 263 days = 11/21/2026
• On transfer day you were 2 weeks 3 days pregnant

The day-3 date is two days later because that embryo was two days younger when it was transferred. A day-6 blastocyst transferred on 03/03/2026 gives 11/18/2026.

For a frozen embryo transfer, use the embryo's age when it was frozen and the date it was transferred to you. The time it spent frozen doesn't count, because the embryo doesn't develop while frozen. A day-5 blastocyst frozen two years ago and transferred on 03/03/2026 gets the same due date as a fresh day-5 transfer on that date: 11/19/2026.

If you're not sure whether your embryo was transferred on day 5 or day 6, check your clinic's transfer report. The difference is one day in the due date.

In a natural pregnancy, a first-trimester ultrasound can move the due date if it disagrees with the last-period estimate. With IVF, ACOG says the date derived from the assisted reproduction should be used, because the timing is already known precisely. That's why this calculator doesn't offer an LMP-vs-ultrasound comparison when you choose IVF.

Your scans still matter: they confirm the pregnancy's location, the heartbeat and how many embryos implanted. If your clinic or OB-GYN gives you a due date, go by theirs, and you can enter it in the pregnancy week calculator as a known due date.

• Your estimated due date with the weekday and days to go
• How far along you are today in weeks + days, your trimester and your ACOG term stage
• The estimated conception date (transfer date minus embryo age) and the LMP-equivalent date your OB-GYN will use
• The dates you reach 37, 40 and 42 weeks
• A timeline of key windows, from the first-trimester screen to the anatomy scan and glucose screening, which you can download as an .ics calendar file
• A link to your current week in pregnancy week by week

The calculation happens in your browser, and your dates aren't uploaded or saved. This tool is informational and is not a substitute for medical advice from your fertility clinic or OB-GYN. If you have heavy bleeding, severe belly or shoulder pain, or feel faint, get care right away; in an emergency, call 911.