Fertility · IVF

IVF Due Date Calculator

Calculate your due date from your embryo transfer date. Supports Day 3 cleavage embryos, Day 5 blastocysts and Day 6 FETs — and shows your current gestational age plus days remaining.

Last reviewed 22 May 2026

IVF / FET due date

Calculate your due date from your embryo transfer

Embryo age at transfer

Enter your embryo transfer date to see your due date and current gestational age.

How to use this calculator

Enter the date of your embryo transfer and pick whether it was a Day 3 cleavage-stage embryo, a Day 5 blastocyst (the most common modern protocol), or a Day 6 blastocyst. The calculator returns your estimated due date, your current gestational age in weeks and days, and the days remaining.

The math

IVF dating is precise because the day of conception is known to the hour. The conventional way to translate it into obstetric record format is to use a 280-day gestation (40 weeks from a notional LMP) and subtract the embryo’s age at transfer:

  • Day 3 embryo: EDD = transfer + 263 days.
  • Day 5 blastocyst: EDD = transfer + 261 days.
  • Day 6 blastocyst (FET): EDD = transfer + 260 days.

The same formulas apply to fresh transfers and frozen-embryo transfers (FET) — only the embryo’s age at transfer matters.

Interpreting your result

Your obstetric team may still verify the EDD with a first-trimester crown-rump-length (CRL) ultrasound between 8 and 13 weeks. In IVF pregnancies the agreement is usually within a day or two; if there is a larger discrepancy the team will discuss whether to use IVF-based or CRL-based dating going forward.

Limitations

  • The standard 280-day gestation is a population average. Real labour begins anywhere from 37 to 42 weeks for most singleton pregnancies, with only ~5 % of babies actually born on the exact EDD.
  • Twin and higher-order multiple pregnancies usually deliver earlier than the calculated EDD.
  • This calculator assumes a successful clinical pregnancy. Early-pregnancy losses don’t change the math but they do change the relevance.

Sources

  • American College of Obstetricians and Gynecologists. Method for estimating due date (Committee Opinion No. 700). Obstet Gynecol 2017;129:e150-4.
  • Practice Committee of the American Society for Reproductive Medicine. Performing the embryo transfer (a committee opinion). Fertil Steril 2017;107:882-96.
  • Royal College of Obstetricians and Gynaecologists / NHS UK. Pregnancy dating after assisted conception.

Frequently asked questions

Why does IVF use different math than a regular due date?
In a natural cycle, conception is estimated from the last menstrual period (LMP) and the standard 14-day luteal phase — Naegele's rule (LMP + 280 days). With IVF, the exact day of fertilisation is known and we work from the embryo transfer date instead. A Day-5 blastocyst transfer effectively starts the clock at conception + 5 days; the formula collapses to EDD = transfer + 261 days.
How is the date different for Day 3 vs Day 5 embryos?
A Day 3 cleavage-stage embryo is two days younger than a Day 5 blastocyst at transfer, so its EDD is two days later: transfer + 263 days for Day 3 vs transfer + 261 days for Day 5. Day 6 blastocysts (frozen-thawed) use transfer + 260 days.
Does fresh vs frozen embryo transfer (FET) change the math?
No. The formula only depends on the embryo's age at transfer, not on whether the embryo was previously frozen. A thawed Day-5 blastocyst FET uses the same +261 days as a fresh Day-5 transfer.
Is the IVF due date more accurate than an LMP due date?
Yes, by a wide margin. With LMP-based dating ovulation is assumed to occur on Day 14, but real ovulation varies. IVF transfers fix conception to a known calendar day. Your obstetric team may still refine the EDD slightly using the first-trimester crown-rump-length (CRL) ultrasound at 8–13 weeks.
What's the equivalent LMP shown by the calculator?
Some obstetric records key off LMP for gestational age. The 'equivalent LMP' is EDD minus 280 days — the conventional menstrual reference point your IVF transfer would correspond to. It's purely a bookkeeping date, not a real period.

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