How is an IVF due date calculated?

An IVF due date is counted from the embryo transfer date, because that is when the pregnancy timeline is fixed. A day-5 transfer uses a blastocyst that has grown for five days, and the due date is 261 days after the transfer. A day-3 transfer uses an embryo two days younger, so the due date is 263 days after the transfer. Both use a due-date timeline of 40 weeks. The known timing is why IVF due dates are often more precise than dates estimated from a last period.

What is the difference between a day-3 and a day-5 transfer?

The number refers to how many days the embryo has developed in the laboratory before being transferred. A day-3 embryo has divided into roughly eight cells. A day-5 embryo has reached the blastocyst stage, with many more cells and a more developed structure. Clinics choose between them based on embryo quality and individual circumstances. For the due date, the two-day difference in embryo age is simply added in, so a day-3 transfer gives a due date two days later than a day-5 transfer on the same date.

Why does IVF have its own due date calculator?

IVF dating uses embryo age and transfer date rather than estimating ovulation from the last period. This tool supports day-3 and day-5 embryo ages. Use the age and assigned due date supplied by your clinic, especially if your embryo age differs from those options.

How accurate is an IVF due date?

The arithmetic uses the known embryo age and transfer date, as recommended by ACOG. It does not predict the actual day of birth. Follow the due date assigned by your fertility clinic; later changes are clinical decisions made only in appropriate circumstances.

Does the IVF due date count from transfer or from conception?

It counts from the transfer date. With IVF, fertilisation happens in the laboratory, and the embryo is then grown for three or five days before being transferred. The calculator builds that laboratory time into the rule it uses, 261 days for a day-5 transfer and 263 days for a day-3 transfer. You do not need to work out a separate conception date. Just enter the transfer date and choose the transfer type.

IVF Due Date Calculator

Estimate a due date using the embryo age and transfer date supplied by your fertility clinic. Supports day-3 and day-5 embryos.

Embryo transfer date

Transfer type

Enter your transfer date to see the due date.

This tool gives an estimate only and is not medical advice. Follow the due date assigned by your fertility clinic.

Related pregnancy tools: Due date · Pregnancy weeks · Trimester dates · IVF due date · Ovulation estimate · Conception estimate

Use embryo age and transfer date, then follow your fertility clinic's assigned due date. This tool supports day-3 and day-5 embryos.

About this calculator

An IVF estimated due date uses the embryo's age and transfer date. For a day-5 embryo, add 261 days to transfer; for a day-3 embryo, add 263 days. Use the embryo age supplied by your clinic. A frozen transfer uses the same age-based calculation; time frozen is not added to embryo age.

ACOG recommends embryo-age and transfer-date dating for pregnancies resulting from assisted reproductive technology. Later changes to an assigned due date are reserved for rare circumstances and are decisions for your clinic. This is still an estimated date, not a prediction of birth. See ACOG dating guidance and the general due-date calculator.

Sources checked 9 October 2026. This tool has not been clinically reviewed.

Read the guide: How day-3 and day-5 IVF due dates differ.

Frequently asked questions

How is an IVF due date calculated?: An IVF due date is counted from the embryo transfer date, because that is when the pregnancy timeline is fixed. A day-5 transfer uses a blastocyst that has grown for five days, and the due date is 261 days after the transfer. A day-3 transfer uses an embryo two days younger, so the due date is 263 days after the transfer. Both use a due-date timeline of 40 weeks. The known timing is why IVF due dates are often more precise than dates estimated from a last period.
What is the difference between a day-3 and a day-5 transfer?: The number refers to how many days the embryo has developed in the laboratory before being transferred. A day-3 embryo has divided into roughly eight cells. A day-5 embryo has reached the blastocyst stage, with many more cells and a more developed structure. Clinics choose between them based on embryo quality and individual circumstances. For the due date, the two-day difference in embryo age is simply added in, so a day-3 transfer gives a due date two days later than a day-5 transfer on the same date.
Why does IVF have its own due date calculator?: IVF dating uses embryo age and transfer date rather than estimating ovulation from the last period. This tool supports day-3 and day-5 embryo ages. Use the age and assigned due date supplied by your clinic, especially if your embryo age differs from those options.
How accurate is an IVF due date?: The arithmetic uses the known embryo age and transfer date, as recommended by ACOG. It does not predict the actual day of birth. Follow the due date assigned by your fertility clinic; later changes are clinical decisions made only in appropriate circumstances.
Does the IVF due date count from transfer or from conception?: It counts from the transfer date. With IVF, fertilisation happens in the laboratory, and the embryo is then grown for three or five days before being transferred. The calculator builds that laboratory time into the rule it uses, 261 days for a day-5 transfer and 263 days for a day-3 transfer. You do not need to work out a separate conception date. Just enter the transfer date and choose the transfer type.

Last updated 2026-10-17

IVF Due Date Calculator

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