IVF Due Date Calculator

Estimate your IVF due date from your egg retrieval or embryo transfer date, using the standard 266-day post-retrieval (38-week) pregnancy dating rule — review the exact date with your fertility clinic.

Quick Facts

Dating rule
266 days from egg retrieval
Equivalent to the standard 280-day (40-week) LMP rule, backdated 14 days to the retrieval/fertilization date.
Transfer-day offsets
Day 3: +263d, Day 5: +261d, Day 6: +260d
Fewer days are added the older the embryo is at transfer.
Trimester bounds
1st: 0-13w6d, 2nd: 14w-27w6d, 3rd: 28w+
Term is generally considered 37w0d-41w6d.

Your Results

Calculated
Estimated due date
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266 days from retrieval
Gestational age
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As of the reference date
Time to due date
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Countdown from reference date
Trimester
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Current stage

Ready

Enter your retrieval or transfer date, then calculate your estimated due date.

About the IVF due date estimate

IVF pregnancies are dated differently from natural conceptions because the exact day of fertilization is known. Egg retrieval marks that day directly, so clinics count forward 266 days (38 weeks) from retrieval to reach the estimated due date, the same 40-week convention used for natural pregnancies but anchored to a known fertilization date instead of an estimated ovulation day. When dating from an embryo transfer instead, the same due date is reached by adding 266 days minus the embryo's age at transfer, because the transfer already happened some days after retrieval.

How the calculation works

  • Egg retrieval (Day 0): due date = retrieval date + 266 days.
  • Day 3 embryo transfer: due date = transfer date + 263 days (266 minus the embryo's 3-day age).
  • Day 5 blastocyst transfer: due date = transfer date + 261 days (266 minus 5 days).
  • Day 6 blastocyst transfer: due date = transfer date + 260 days (266 minus 6 days).

Putting the result in context

This due date is an estimate for planning, not a guarantee — most pregnancies deliver anywhere within a normal range around it, not on the exact day. Your clinic's own records (and any early ultrasound measurement) are the authoritative source, since ultrasound can confirm gestational size directly rather than backdating from the procedure calendar. Use this calculator to sanity-check a date or plan ahead between appointments, not to override what your clinic tells you.

When to consult a professional

This tool performs the standard IVF dating arithmetic only. It does not assess embryo quality, pregnancy viability, or any medical risk. For confirmation of your due date, monitoring of the pregnancy, or any concerning symptoms, consult your fertility clinic or obstetric provider directly.

Frequently Asked Questions

How is an IVF due date calculated?
IVF due dates are dated from a known event, egg retrieval or embryo transfer, rather than from the last menstrual period. The standard rule adds 266 days (38 weeks) to the egg retrieval date, since retrieval marks the day of fertilization. From a transfer date, the same due date is reached by adding 266 days minus the embryo's age at transfer: 263 days for a Day 3 transfer, 261 days for a Day 5 blastocyst transfer, or 260 days for a Day 6 transfer.
Why isn't the due date based on my last menstrual period?
In a natural pregnancy the exact conception date is usually unknown, so due dates are estimated from the last menstrual period using Naegele's rule, which adds 280 days and assumes ovulation around cycle day 14. IVF pins down the fertilization date exactly through egg retrieval, so clinics date from that known day instead of an estimated last period, which removes the cycle-length guess.
What is the difference between a Day 3 and a Day 5 transfer?
A Day 3 transfer places a cleavage-stage embryo, while a Day 5 or Day 6 transfer places a blastocyst that has developed for two or three additional days in the lab. Because the embryo is older at transfer, fewer days are added from that transfer date to reach the same due date as an egg-retrieval-based estimate.

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