IVF Due Date Calculator
Enter your IVF milestone date to estimate your pregnancy due date, gestational age, and countdown.
How to calculate due date from IVF
When pregnancy happens through IVF, the due date can be estimated more precisely than in many spontaneous pregnancies because the date of fertilization or embryo transfer is known. Instead of guessing from a last menstrual period alone, IVF pregnancy dating uses a specific timeline tied to your treatment.
This page gives you a practical IVF due date calculator and explains the exact math behind it. Whether you had a fresh transfer or frozen embryo transfer (FET), the method is the same: start with a known IVF date and add the right number of days.
IVF due date formulas (simple and accurate)
1) If you know egg retrieval or fertilization date
- Estimated due date = retrieval/fertilization date + 266 days
2) If you know embryo transfer date
- Due date = transfer date + (266 - embryo age in days)
Examples:
- Day 3 transfer: add 263 days
- Day 5 transfer: add 261 days
- Day 6 transfer: add 260 days
| IVF Event Used | Formula | What It Means |
|---|---|---|
| Egg retrieval / fertilization date | Date + 266 days | Starts from conception timing |
| Day 3 embryo transfer | Transfer date + 263 days | Embryo already 3 days old at transfer |
| Day 5 embryo transfer | Transfer date + 261 days | Most common blastocyst transfer timing |
| Day 6 embryo transfer | Transfer date + 260 days | Used for later-stage blastocyst transfer |
Why IVF dating differs from natural conception dating
In a non-IVF pregnancy, providers often estimate due date from the first day of the last menstrual period (LMP), assuming ovulation happened about 14 days later. But in IVF, fertilization timing is known much more clearly. That is why calculate pregnancy due date from embryo transfer is usually more reliable early on.
Even so, a due date is still an estimate. Most babies do not arrive exactly on that day. Delivery can naturally occur before or after the predicted date.
Step-by-step example (Day 5 transfer)
Let’s say your frozen embryo transfer took place on March 10 and it was a Day 5 blastocyst.
- Embryo age at transfer = 5 days
- Add 261 days to transfer date
- Your estimated due date is in early December
Your clinic may also discuss gestational age at transfer. For a Day 5 transfer, gestational age is considered approximately 2 weeks + 5 days on transfer day.
Fresh transfer vs frozen transfer due date
People often ask if a frozen embryo transfer changes due date calculation. In terms of math, no. The key variable is embryo age at transfer. A Day 5 FET and a Day 5 fresh transfer use the same day-count approach for estimated due date.
Keywords you may see online include:
- IVF due date calculator day 5 transfer
- FET due date calculator
- calculate weeks pregnant after IVF transfer
- IVF conception date calculator
What if ultrasound dating is different?
Early ultrasounds are often used to confirm viability and growth. Sometimes measurements may differ slightly from calculated dates due to normal biological variation and measurement limits. Your fertility clinic or OB team decides the official clinical dating used in your records.
If your provider gives you a due date that differs from this calculator, always follow your care team’s official date.
Frequently asked questions
Is the IVF due date exact?
No due date is exact. It is an estimated date based on known IVF timing. Many births occur in the two weeks before or after this date.
Can I calculate due date from IVF transfer only?
Yes. That is one of the most common and practical methods. Just include embryo age at transfer for best accuracy.
How do I calculate gestational age after IVF?
After finding conception/fertilization date, gestational age is usually counted as conception date plus 14 days (LMP convention). The calculator above does this automatically.