IVF Due Date Calculator

What this calculator does

This calculator estimates your expected delivery date from an IVF, frozen embryo transfer (FET), or IUI (intrauterine insemination) procedure. Enter the transfer/insemination date and the embryo type; the tool produces the due date plus a milestone table showing when you will reach 12, 20, 28, 32, and 40 weeks of gestation.

All math is plain date arithmetic running on your device. No information leaves the browser tab.

How IVF dating works (and why it differs from natural)

Natural-conception pregnancies are dated from the first day of the last menstrual period (LMP) plus 280 days. This is the conventional 40-week count. It works because the exact ovulation date is rarely known precisely, and LMP is something patients can usually remember. The “due date” is really LMP + 280 days, with ovulation assumed to occur around day 14 of the cycle.

For IVF, the exact moment of conception is known — it’s the day of fertilization in the lab, which equals the egg-retrieval date for fresh cycles. The embryo is then cultured for 3 or 5 days before transfer, and the due-date math works backward from that:

• Day 3 embryo transfer (fresh): transfer date + 263 days = due date
• Day 5 blastocyst transfer (fresh): transfer date + 261 days
• Frozen Embryo Transfer Day 3: transfer date + 263 days
• Frozen Embryo Transfer Day 5: transfer date + 261 days
• IUI (intrauterine insemination): IUI date + 266 days

All five values equate to the same 40-week gestational age counted from the equivalent LMP. The day count just adjusts for how many days the embryo had already developed before transfer. (Day 3 = 14 ovulation days − 3 culture days = 11 days into the conventional cycle plus 263 = LMP + 280. Same arithmetic for Day 5.)

What to expect at each milestone

The calculator displays five key dates:

• 6-8 weeks (after first positive test): your fertility clinic typically performs the first ultrasound here. They measure crown-rump length (CRL) and compare against your transfer-based date. If the CRL ages disagree by more than 5 days, the clinic adopts the CRL date as official. This is also when the first heartbeat is visible (around 6 weeks).
• 12 weeks: end of the first trimester. Most clinics transition you from fertility-clinic care to a regular OB/GYN at this point. Miscarriage risk drops substantially after this milestone (from ~25% in early pregnancy to <2% after 12 weeks).
• 20 weeks: anatomy scan / mid-pregnancy ultrasound. Sex determination, fetal anatomy survey, anomaly screening.
• 28 weeks: start of the third trimester. Standard glucose challenge test, more frequent appointments begin.
• 32 weeks: prenatal appointments become weekly. Most clinics start fetal-position monitoring.
• 40 weeks: the estimated due date itself.

Accuracy and what’s actually predictable

The IVF transfer-date arithmetic is exact, but delivery dates are not. Only about 5% of babies are born on their estimated due date. The typical delivery window is 38 to 42 weeks gestation. A few factors affect this:

• Multiple gestation: twins typically deliver around 36-37 weeks; triplets around 32-34 weeks. Multi-embryo transfers have higher rates of preterm delivery. If your transfer was multi-embryo, discuss expected timeline with your clinic.
• Previous preterm birth: raises preterm-birth risk for the current pregnancy.
• Cervical and uterine conditions: can affect timing.
• Spontaneous labor onset varies normally within a 4-week window — the body decides when, and the due date is the midpoint of that range, not a guarantee.

The calculator’s due date is what to plan around — schedule maternity leave, organize childcare, prepare for delivery. The actual delivery date will be within a few days to a few weeks of that.

Why dating accuracy matters

Accurate gestational age dating affects clinical decisions throughout the pregnancy:

• Timing of routine ultrasounds (anatomy scan at 18-22 weeks requires accurate dating).
• Screening test windows — first-trimester screening (NT scan + blood test) only works in a narrow gestational-age window.
• Decisions about induced labor — induction policies typically apply at 39+ weeks for routine elective inductions, 41+ for medical indications.
• Preterm vs term classification — 37+ weeks is term; under 37 is preterm.

For all of these, the ultrasound at 6-8 weeks is the gold standard. The transfer-date math here gives you a planning estimate before that ultrasound confirms.

Privacy

Fertility data is among the most sensitive personal information a person handles. This calculator does plain date arithmetic in JavaScript on your device — transfer date plus a fixed number of days, no API call, no analytics, no logging. Switch off Wi-Fi after the page loads and the tool keeps working. Your transfer date and embryo type stay on your device.