IVF Due Date Calculator
Calculate your estimated due date from your egg retrieval day or embryo transfer date — plus a full timeline of the milestones ahead, built specifically around how IVF pregnancies are actually dated.
Quick answer
An IVF due date is calculated from the embryo transfer date plus the number of days left to reach 266 total days of development: 263 days for a Day 3 transfer, 261 days for a Day 5 transfer, and 260 days for a Day 6 transfer. If you only know your egg retrieval date, simply add 266 days — retrieval day is treated as the fertilization day. Fresh and frozen (FET) cycles use the exact same formula.
Why IVF dating is different — and more precise
A natural pregnancy is dated from the last menstrual period because that is usually the only reliable date available; ovulation is estimated, not known. IVF flips that around. Your clinic knows the exact day your egg was retrieved and, if applicable, the exact age of the embryo transferred. That precision is why fertility specialists consider IVF-based dating generally more reliable than LMP-based dating, typically accurate to within a few days rather than a week or more.
Egg retrieval method
Retrieval day is treated as the day of fertilization. Add 266 days directly — the same conception-to-birth interval used for naturally conceived pregnancies.
Embryo transfer method
Because the embryo is already a known number of days old at transfer, that age is subtracted from the 266-day interval: 263 days for Day 3, 261 for Day 5, 260 for Day 6.
Theoretical LMP: why your forms ask for it
Medical intake forms often ask for a “last menstrual period” date even though IVF pregnancies do not rely on that number. Clinics calculate a theoretical LMP so that gestational-age language stays consistent with naturally conceived pregnancies on paperwork and ultrasound reports — it is simply 14 days before your egg retrieval date (or embryo age plus 14 days before transfer). This calculator works that number out for you automatically.
Fresh vs. frozen: does it change your due date?
- No. Fresh and frozen embryo transfers (FET) use the exact same due-date formula.
- The only thing that matters is the embryo’s developmental age at the moment of transfer, not whether it had been frozen.
- ICSI (intracytoplasmic sperm injection) also has no effect on dating — only fertilized embryos are transferred either way.
- Donor-egg and donor-embryo cycles follow the same formula based on the recipient’s transfer or retrieval date.
Methodology
- You choose the date you actually have on file: egg retrieval day or embryo transfer day, both documented by your clinic.
- From retrieval, 266 days are added directly, treating retrieval as the fertilization date.
- From transfer, the calculator adds 266 days minus the embryo’s age at transfer (3, 5, or 6 days), consistent with the formulas fertility clinics commonly use.
- A theoretical LMP is derived by subtracting 14 days from the equivalent fertilization date, for consistency with standard gestational-age paperwork.
- Current gestational age, days remaining, and the beta hCG testing window are calculated relative to today’s date and update automatically as you change any input.
- The multiples note reflects general population data on typical delivery timing for singleton, twin, and triplet pregnancies — it does not change the due-date calculation itself.
Frequently asked questions
Add 261 days to your transfer date. This comes from the standard 266-day fertilization-to-birth interval minus the 5 days the blastocyst had already developed before transfer.
IVF-based dating is generally considered more accurate than natural pregnancy dating, often within a few days, because the exact fertilization or transfer date is a documented medical fact rather than an estimate of ovulation timing. A first-trimester ultrasound remains the gold standard for confirming it.
The due-date formula itself is the same regardless of how many embryos were transferred. What changes in practice is that twin and triplet pregnancies more often deliver before the calculated due date, so many providers plan around an earlier expected delivery window even though the formula hasn’t changed.
Most clinics schedule the first blood beta hCG test 10 to 14 days after transfer, with a second test about 48 hours later to confirm the level is rising appropriately, rather than relying on the first result alone.
No. Fresh and frozen (FET) transfers use the identical due-date formula. Only the embryo’s age at the moment of transfer affects the calculation, not whether it was ever frozen.
Add 266 days to your egg retrieval date. Retrieval day is treated the same way a natural conception date would be, since fertilization typically happens within hours of retrieval.
A theoretical LMP is a calculated stand-in last-period date, used so IVF pregnancy paperwork and gestational-age language stay consistent with naturally conceived pregnancies. It is simply 14 days before your fertilization-equivalent date, whether that is retrieval day or the back-calculated transfer date.
A Day 3 embryo is 2 days younger at transfer than a Day 5 blastocyst, so its due-date formula adds 2 more days: 263 days for Day 3 versus 261 days for Day 5. A Day 6 blastocyst transfer adds 260 days.
No. Intracytoplasmic sperm injection (ICSI) is a fertilization technique used in the lab; it does not change the embryo’s age or the transfer date, so it has no effect on due-date dating.
It can, though it is less common than with natural conception since IVF dating is already precise. If a first-trimester ultrasound measurement disagrees meaningfully with the transfer-based estimate, your provider may adjust the due date to match the scan.
More maternal health calculators
This IVF due date calculator is one tool inside a full set of pregnancy, fertility, and postpartum calculators I’ve built and organized into one hub. Explore the full collection any time.
References
- American College of Obstetricians and Gynecologists (ACOG). Committee Opinion No. 700 — Methods for Estimating the Due Date.
- American Society for Reproductive Medicine (ASRM). Patient guidance on embryo transfer dating and gestational age calculation in IVF.
- Mayo Clinic. IVF and frozen embryo transfer pregnancy dating guidance.
- NIH / MedlinePlus. Assisted reproductive technology and pregnancy dating overview.
- CDC. ART (assisted reproductive technology) success rates and multiple-birth delivery statistics.