IVF Due Date Calculator
Get an accurate estimated delivery date based on your Day 3 or Day 5 embryo transfer — the dating method recommended by fertility clinics, more precise than standard LMP-based calculators for IVF pregnancies.
Calculate Your IVF Due Date
How Day 3 and Day 5 Transfers Are Dated
Your Pregnancy Milestone Timeline
Why IVF Due Dates Are Calculated Differently
Most online due-date calculators rely on the first day of your last menstrual period (LMP) and Naegele’s rule, assuming a 28-day cycle and ovulation around day 14. IVF pregnancies skip that guesswork — your clinic knows the exact day of fertilization, so your due date can be calculated directly from your embryo transfer date instead of an estimated ovulation date.
This is why fertility clinics and reproductive endocrinologists use embryo-age-based dating, recommended in American Society for Reproductive Medicine (ASRM) and ACOG guidance on assigning the estimated due date (EDD) for assisted reproductive technology (ART) pregnancies.
The Formula
- Day 3 (cleavage-stage) transfer: Due date = transfer date + 263 days
- Day 5 (blastocyst) transfer: Due date = transfer date + 261 days
Both formulas land on the same 266 days of development measured from fertilization (the day of egg retrieval), which is equivalent to the standard 280-day pregnancy measured from LMP.
Fresh vs. Frozen Embryo Transfer: Does It Change Dating?
🧊 Frozen Embryo Transfer (FET)
- Embryo age is precisely known from the day it was frozen
- Dating uses the embryo’s developmental age at thaw/transfer (Day 3 or Day 5), not the FET cycle start date
- Most common transfer type today, and the most precisely dated
🌱 Fresh Transfer
- Transfer happens 3–5 days after egg retrieval in the same cycle
- Same Day 3 / Day 5 formula applies directly
- Equally accurate — fresh vs. frozen affects the pregnancy course, not the dating math
What If I Used a Donor Egg or Gestational Carrier?
The same Day 3/Day 5 dating formula applies — due dates are calculated from the embryo’s developmental age, not the egg source or who is carrying the pregnancy. Always confirm your due date with your reproductive endocrinologist or OB at your first prenatal ultrasound, which remains the gold-standard confirmation regardless of conception method.
How Accurate Is IVF Dating Compared to LMP Dating?
IVF dating is generally considered more accurate than LMP-based dating because the exact day of fertilization is known, removing the variability of ovulation timing that affects natural-cycle estimates. Your clinic’s dating ultrasound, typically performed around 6–8 weeks, will usually confirm — and rarely needs to adjust — an IVF-calculated due date.
Frequently Asked Questions
Pregnancy apps usually default to LMP-based dating with an assumed 28-day cycle. If you enter your actual transfer date and select “Day 3” or “Day 5,” most apps will recalculate correctly — but double-check by entering it as an IVF/conception date, not an LMP date.
It’s uncommon, but possible. Because your transfer date is exact, IVF dating is already highly precise, so most clinics keep the IVF-calculated due date unless the dating ultrasound measurement differs significantly.
Many medical and insurance forms are formatted around a last menstrual period field. Your LMP-equivalent date is simply your due date minus 280 days — it lets you complete those forms accurately even though conception occurred via embryo transfer, not a natural cycle.
The calculated due date is the same, but twin pregnancies are statistically more likely to deliver earlier than singleton pregnancies, typically in the 36–37 week range. Your OB will adjust your monitoring schedule accordingly.
A Day 6 blastocyst transfer is typically dated as transfer date + 260 days (one day less than Day 5). If your embryo was transferred on Day 6, confirm the exact adjustment with your clinic.
Reviewed by Dr. Ruqaiya Khan, MD, FACOG
Dr. Khan reviews all medical content on PregCalc for clinical accuracy, including dating methodologies used in assisted reproductive technology (ART) pregnancies. This page was last medically reviewed in June 2026.
- American Society for Reproductive Medicine (ASRM) — guidance on estimated due date assignment for ART pregnancies
- American College of Obstetricians and Gynecologists (ACOG) — Committee Opinion on methods for estimating due date
- Mayo Clinic — pregnancy dating and trimester definitions
- NHS — IVF and fertility treatment pregnancy guidance