IVF Due Date Calculator (FET)

How Does the IVF Due Date Calculator Work?

Modern assisted reproduction technologies have helped countless couples experience parenthood.

Most couples going through IVF procedures are eagerly awaiting their due date to meet their child finally. The pregnancy calendar allows you to determine the date of birth of the baby.

With the correct determination of the timing of pregnancy, doctors and the expectant mother know in advance the approximate date of the onset of labor.

This allows them to prepare for this process, identify possible complications and choose the appropriate delivery method.

That is why it is so necessary for pregnant women to regularly visit a doctor as part of an IVF program and calculate their due dates.

What is the IVF Due Date Calculator Based On?

Naegele’s Rule Calculator and Mathematical Method

First, let’s briefly discuss how the due date is calculated in the case of natural conception and then compare it to the IVF calculator.

The average duration of pregnancy week range is approximately 36 to 42 weeks. The average number is 40 weeks or 280 days.

In the case of natural conception, treatment with fertility drugs or IUI (intrauterine insemination), due date calculations are based on the first day of LMP.

On the last day of your menstrual period, the due date can be calculated according to the following:

Naegele’s Rule

This method works best in cases where the patient has a regular (28 day) menstrual cycle without significant fluctuations.

3 months are subtracted from the first date of the last monthly period and 7 days and 1 year are added.

Mathematical method

IVF Due Date Calculator - mathematical method

IVF Due Date Calculator – mathematical method

Just by adding the average period of pregnancy – 280 days to the start date of the last menstrual period, you can get the estimated date of birth.

On the other hand, in the case of IVF, everything is much easier since we know the exact date of conception as it is done artificially in the lab.

Therefore, tracking ovulation is not needed like it is for a natural pregnancy.

The start dates are scheduled and due date calculation is possible just by adding 266 days to the egg retrieval or embryo transfer date.

To use the IVF due date calculator, you need an exact date of one of the following:

IVF with own eggs

In this case, where eggs are retrieved from the mother rather than a donor and then fertilized in the lab, 266(38 weeks) days are added.

Egg retrieval date + 266 days

Day 3 embryo transfer or day 3 FET (Frozen Embryo Transfer)

An embryo consisting of several cells is transferred 3 days after fertilization. Since the embryo is considered to be 3 days already “old,” 263 days are added to the IVF transfer date in this case instead of 266.

Transfer date + 263 or Transfer date + 266 – 3

Day 5 embryo/blastocyst transfer or day 5 FET

The embryo is transferred 5 days after fertilization. Since the embryo is considered to be 5 days already “old” 261 days are added to the transfer date in this case instead of 266 days.

Transfer date + 261 or Transfer date + 266 – 5

IVF with fresh donor egg cycle

In this instance, where the donor’s eggs are fertilized, 266 days are added.

Egg retrieval date + 266 days

Fresh donor embryo cycle

Consisting of retrieval and fertilization of donor eggs, 266 days (38 weeks) are added.

Egg retrieval date + 266 days

Confidence of IVF Due Date Calculator

Although IVF due date calculation estimates are typically much more accurate than pregnancies following natural conception, the calculator alone does not guarantee absolute accuracy.

In any case, a detailed medical examination is required to confirm the probable due date.

The actual due date is based on factors like the health of the mother and fetus, the number of fetuses, the mother’s hormonal balance, fetal positions, and so on.

Therefore, the IVF due date calculation is an estimate, likely to be within +/- 2 weeks accuracy.

Estimating a baby’s due date of the day with the help of an IVF due date calculator aids the pregnant mother herself, in general terms, in planning her pregnancy.

Every pregnancy is individual and unique in its way. Thus, the prognosis can not be the same for every IVF pregnancy due date.

That’s why you need constant communication with your physicians and fertility doctor and midwife during the pregnancy period. Only about 5% of babies arrive on their estimated due date.

Multiple Gestations

In cases of multiple gestations (twins, triples, etc.), the IVF due date formula changes since a more significant number of gestations raise the risk for a shorter pregnancy.

After using the rule above of adding 266 days (minus 3 days in a 3-day embryo, minus 5 days in a 5-day embryo)

In the case of twins, we subtract 21 days from that number.

In the case of triplets, we subtract 49 days from that number.


By using the grantsformedical.com’s calculator, documentation and/or any software found therein, the User agrees to abide by grantsformedical.com’s Terms and Conditions.

This calculator is for informational purposes only and should be used only for estimations. Differences in calculations can have enormous clinical consequences. These tools do not give professional or healthcare advice. This information is not intended to replace clinical judgment or guide individual patient care in any manner.

Your reliance upon information and content obtained by you at or through this website is solely at your own risk. Neither Five Buttons, LLC nor grantsformedical.com shall be liable for any special, consequential, damage or injury (including death) to you, other persons or exemplary damages resulting in whole or part from any User’s use of or reliance upon this calculator and the information contained within.

grantsformedical.com and the system’s authors, developers and distributors assume no responsibility for any erroneous results due to defects in the system. Access to and use of the grantsformedical.com is provided without warranty of merchantability or fitness for any particular purpose or any other warranty, express or implied.

See Also

How Much Does IVF Cost?

Grants for IVF

Loans for IVF





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