IVF Due Date Calculator
Calculate an IVF due date from the embryo transfer date and the embryo's age in days at transfer.
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What this tool does
Calculate an IVF due date from the embryo transfer date and the embryo's age in days at transfer. Standard IVF dating arithmetic: conception (fertilisation) is day 0 and the LMP equivalent is 14 days before it. Your fertility clinic's dating takes precedence.
How to use the IVF Due Date Calculator
- Enter or select embryo transfer date (yyyy-mm-dd).
- Enter or select embryo age at transfer.
- Read the calculated result; change any measurement to compare alternatives.
Formula
due date = transfer date + (266 − embryo age in days); gestational age at transfer = embryo age + 14 days
- transfer
- Embryo transfer date (YYYY-MM-DD)
- embryo
- Embryo age at transfer
Standard IVF dating arithmetic: conception (fertilisation) is day 0 and the LMP equivalent is 14 days before it. Your fertility clinic's dating takes precedence.
Worked example
For ivf due date calculator, the following measurements illustrate the exact method: Embryo transfer date (YYYY-MM-DD): 2026-10-01; Embryo age at transfer: 5.
Inputs
- Embryo transfer date (YYYY-MM-DD)2026-10-01
- Embryo age at transferDay 5 (blastocyst)
Result
- Estimated due date2027-06-19
- Gestational age on transfer day2 weeks 5 days (embryo day 5 + 14)
Results explained
- Estimated due date
- Estimated due date from the formula above. Standard IVF dating arithmetic: conception (fertilisation) is day 0 and the LMP equivalent is 14 days before it. Your fertility clinic's dating takes precedence.
- Gestational age on transfer day
- Gestational age on transfer day from the formula above. Standard IVF dating arithmetic: conception (fertilisation) is day 0 and the LMP equivalent is 14 days before it. Your fertility clinic's dating takes precedence.
Frequently asked questions
Pregnancy is dated as if fertilisation were day 14 of a cycle. Due date = transfer date + 266 − embryo age: a day-5 transfer adds 261 days, a day-3 transfer adds 263.
Gestational age counts from a notional LMP two weeks before fertilisation, so on transfer day you are 2 weeks + the embryo's age — e.g. 2 weeks 5 days for a blastocyst transfer.
The same formula applies using the embryo's developmental age at transfer (usually day 5 or 6), regardless of how long it was frozen.
Yes — fertilisation and transfer dates are known exactly, removing ovulation guesswork. Clinics still confirm growth by ultrasound.
The due date arithmetic is identical; twin pregnancies often deliver earlier, which your clinic will plan around.