IVF Due Date Calculator
Estimate an IVF due date from an embryo transfer, egg retrieval, or fertilization date. Choose your IVF method and enter the relevant date to see your due date and pregnancy milestones.
Estimate Your Due Date from an IVF Date
IVF Due Date Formula
Where:
- \(D\) — estimated due date
- \(T\) — entered transfer, retrieval, or fertilization date
- \(a\) — embryo age in days on the entered date: 3, 5, or 6 for a transfer; 0 for retrieval or fertilization
- \(L\) — equivalent last menstrual period (LMP) date
The calculation places the due date 266 days after fertilization, or the corresponding number of days after an embryo transfer. The equivalent LMP is a dating reference, not necessarily the date of an actual period.
IVF Due Date – Calculation Example
Example: a day-5 blastocyst is transferred on September 15, 2026, using the calculator’s default settings.
\[D = \text{September 15, 2026} + (266-5)\text{ days} = \text{June 3, 2027}\]
\[L = \text{June 3, 2027} - 280\text{ days} = \text{August 27, 2026}\]
Result: the estimated due date is June 3, 2027, and the equivalent LMP date is August 27, 2026. The 20-week mark falls on January 14, 2027.
How to use the calculator
- Under IVF method, choose Day-3 embryo transfer, Day-5 blastocyst transfer, Day-6 blastocyst transfer, Egg retrieval, Fresh donor egg, or Frozen donor egg.
- Enter the relevant day in Transfer, retrieval, or fertilization date. For a frozen donor egg, enter its fertilization date after thawing if you are using a day-0 date—not the date it was originally retrieved.
- If you selected a donor egg method, set Donor egg date type to Embryo transfer date or Egg retrieval or fertilization date (day 0), as appropriate.
- If the donor egg date is an embryo transfer, choose Day 3, Day 5, or Day 6 under Embryo age at donor egg transfer. This is the embryo’s age on the transfer date.
- Read Estimated due date alongside the equivalent LMP date, current gestational age, trimester, and milestone dates. Check that the entered date and method match your clinic’s records.
Understanding an IVF due date
An IVF due date uses a known treatment date and the embryo’s age instead of estimating conception from a menstrual period. A day-5 transfer, for example, is treated as occurring five days after fertilization, so the calculator adds 261 days to the transfer date. For egg retrieval or fertilization entered as day 0, it adds 266 days. A fresh donor egg retrieval is treated as day 0; for a frozen donor egg, day 0 is fertilization after thawing.
Pregnancy is conventionally described in gestational weeks counted from an LMP date, roughly two weeks before fertilization. The calculator therefore places the equivalent LMP 280 days before the due date. It uses that reference to calculate gestational age and trimester for today, plus the end of the first trimester at 13 weeks and 6 days. The equivalent LMP does not imply that you had a menstrual period on that day.
The other dates are milestones, not appointments: the anatomy scan date is the 20-week mark, 37 weeks marks early term, and 39 weeks marks the start of full term. An estimated due date is a reference point rather than a prediction of the exact day of birth. If you want to compare dating methods, the Pregnancy Due Date Calculator offers a general pregnancy date estimate.
Assumptions and practical tips
Use the embryo’s actual age at transfer, not the number of days since you began medication or since an egg was frozen. For donor egg cycles, the Donor egg date type determines whether the entered date represents a transfer or day 0. Selecting the wrong type can shift the estimate by several days. Check your transfer summary if you are unsure whether the embryo was day 3, day 5, or day 6.
The calculation assumes a 266-day interval from fertilization to the due date. It does not account for individual differences in pregnancy length, a clinic’s revised dating, or decisions about scan timing. Your fertility or maternity care team can confirm which due date should be used in your medical record. The displayed 20-week date is a gestational milestone; it does not mean your anatomy scan must happen on that exact day.
Current gestational age and trimester update with the day you view the calculator. If the entered IVF date is in the future, gestational age is not yet shown; well beyond the expected pregnancy window, it is no longer treated as a current pregnancy. For other stage-specific calculations, see the hCG Doubling Time Calculator for serial early blood tests or the Fetal Weight Estimate Calculator for later ultrasound measurements.
Frequently Asked Questions
How many weeks pregnant am I on the day of an embryo transfer?
On a day-3 transfer, gestational age is 2 weeks and 3 days; on a day-5 transfer, it is 2 weeks and 5 days; and on a day-6 transfer, it is 2 weeks and 6 days. Pregnancy weeks include a conventional two weeks before fertilization, even though the embryo has existed for only a few days.
Does freezing an embryo change its IVF due date?
No. Time spent frozen does not add to the embryo’s age. Use its age when it was transferred—for example, day 5 for an embryo frozen as a day-5 blastocyst and later transferred at that stage. If your clinic recorded a different embryo age or adjusted its dating, use the clinic’s records rather than counting the time in storage.
Why does my ultrasound due date differ from my IVF due date?
Small differences can arise from measurement variation, especially in early ultrasound scans. IVF dating is usually based on well-documented treatment dates, so a scan does not automatically replace it. Your care team will decide which due date belongs in your medical record and whether a larger discrepancy needs follow-up. Do not change your due date based on a scan measurement alone.
Is the due date different for IVF twins?
The estimated due date is calculated the same way for twins as for a single pregnancy, using the treatment date and embryo age. Twins are more likely to be born before that date, however, and their monitoring and delivery plans may differ. Ask your maternity care team which dates to use for scans and other decisions.
What if egg retrieval and fertilization happened on different calendar dates?
A difference of one calendar day can shift an estimate by one day, depending on which date you enter. Clinics commonly date embryo development from egg retrieval or insemination as day 0, but the exact dates in your records may differ. Check your embryology report or ask your clinic which date and embryo age it uses for pregnancy dating.
Do leap years or time zones affect an IVF due date?
Leap days are included when you count calendar days, so adding a fixed number of days may land on a different month and day than expected from a rough months-based estimate. Time zones rarely matter for a recorded clinic date, but a procedure near midnight may appear under different dates in different records. Use the calendar date documented by your clinic.