IVF Due Date Calculator
This IVF due date calculator instantly estimates your due date and key pregnancy milestones, with everything calculated privately in your browser.
Medically reviewed by Kimberly Langdon, MD · Updated 08 September, 2026
Everything is worked out in your browser. Nothing you enter is stored, sent or shared with anyone.
The short version
Your due date is your transfer date plus 263 days for a Day 3 embryo, or plus 261 days for a Day 5 blastocyst.
An IVF due date is the most precise kind there is, because the date of conception was recorded rather than estimated from a period¹.
It is still an estimate. Only about 5% of babies arrive on the exact date, and roughly two thirds arrive within a week either side of it².
A frozen transfer is dated exactly like a fresh one. Time spent in storage does not count towards gestational age.
If your clinic gives you a different date, follow theirs. They have your scans; this page has two numbers you typed in.
Why IVF due dates are counted from your transfer
A standard due date calculator works backwards from the first day of your last menstrual period, because in a spontaneous pregnancy that is the only fixed date anyone has. IVF removes the guesswork: your clinic knows the exact day the embryo was fertilised and the exact day it was transferred, so the count starts from the transfer instead.
That is why this calculator and an ordinary pregnancy app can disagree by a week or more. The app is estimating an ovulation date you never had; your clinic is working from a date it wrote down.
The professional guidance says the same thing. Where a pregnancy results from assisted reproductive technology, the due date is assigned from the known age of the embryo and the date of transfer rather than from a period — IVF being the one case where conception is documented rather than inferred¹.
How this calculator works
Day 3 embryo transfer
Transfer date + 263 days
Day 5 blastocyst transfer
Transfer date + 261 days
Both transfer types work back to the same fixed point: a due date falls 266 days after conception. A Day 3 embryo is transferred three days after fertilisation, so its due date is 263 days after transfer; a Day 5 blastocyst is transferred five days after fertilisation, so its due date is 261 days after transfer. Every other date above is measured from that same 40-week gestational clock — the first ultrasound window at 6 to 7 weeks, the end of the first trimester at 13 weeks 6 days, the viability milestone at 24 weeks, the third trimester at 28 weeks, and the full term window between 39 and 40 weeks. Full term is defined as 39 0/7 to 40 6/7 weeks⁶.
Day 3 and Day 5 are the usual options: embryos are transferred either at the cleavage stage, three days after fertilisation, or at the blastocyst stage, five days after fertilisation⁵. Day 6 and Day 7 blastocysts follow the same rule, and choosing the day of egg retrieval simply counts the full 266 days from fertilisation itself.
All of it is arithmetic performed in your browser. Nothing you type leaves your device, and nothing is stored.
How accurate is an IVF due date?
In a study of 18,708 births following spontaneous labour, only 5% arrived on the estimated date of birth, and roughly 66% arrived within seven days either side of it. That held regardless of which dating method was used or how early in the pregnancy the dating was done. A due date describes the centre of a distribution; it is not an appointment, and a date arrived at from an embryo transfer is no exception².
Do IVF babies arrive early?
This is the question where the honest answer is more complicated than most pages admit. Reviewing the perinatal risks of assisted reproduction, ACOG cites a meta-analysis of 15 studies that found roughly double the odds of preterm delivery in IVF pregnancies after adjusting for maternal age and parity (odds ratio 2.0, 95% confidence interval 1.7–2.2)³.
Two caveats matter as much as the number. The same document states plainly that it remains unclear how much of the association is caused by the treatment itself rather than by the underlying infertility that led to it. And the single largest driver of early arrival after fertility treatment is carrying more than one baby, which is far more common after IVF than after spontaneous conception³.
What the milestone dates actually mean
Viability is not a line a pregnancy crosses on a particular Tuesday. ACOG and SMFM describe the periviable period as 20 0/7 to 25 6/7 weeks, across which reported survival to discharge climbs steeply — roughly 23–27% at 23 weeks, 42–59% at 24 weeks and 67–76% at 25 weeks. Outcomes at any of those points depend on much more than gestational age, including birth weight, whether it is a single baby, where the birth happens, and the decision to provide active resuscitation. The 24-week marker in the calendar above is a widely used reference point, not a threshold⁴.
Common questions about IVF due dates
On the day of a Day 3 transfer you are counted as 2 weeks and 3 days pregnant; after a Day 5 blastocyst transfer you are 2 weeks and 5 days. That sounds odd when the embryo is only days old, but pregnancy is dated from a notional last menstrual period two weeks before conception, so the clock is already running on transfer day. Two weeks later, around your beta hCG test, a Day 5 transfer puts you at roughly 4 weeks and 5 days.
No. The maths depends only on how many days the embryo had been developing when it was transferred, not on whether it was fresh or previously frozen. A frozen Day 5 blastocyst is dated exactly like a fresh one: transfer date plus 261 days. Time spent in storage does not count towards gestational age.
Pick Day 6 or Day 7 in the calculator above and it will work the date out for you. The rule is the same whichever day it was: subtract the embryo’s age in days from 266 and count forward from the transfer, so a Day 6 transfer lands on the transfer date plus 260 days and a Day 7 transfer plus 259.
The same way. What matters is how old the embryo was when it was transferred, not whose egg it came from, so a Day 5 donor-egg blastocyst is still transfer date plus 261 days. If you would rather count from the egg retrieval, choose “Day of egg retrieval” in the calculator above — the due date is then 266 days from the day of retrieval.
Clinics sometimes count from the egg retrieval rather than the transfer, round part-days differently, or revise the date after an early scan. A day or two either way is normal and rarely changes anything about your care. Where the two disagree, use your clinic’s date — it is the one your notes and appointments are built around.
References
Every clinical figure on this page traces to one of the following. Links go to the primary source rather than to a summary of it.
Committee Opinion No. 700: Methods for Estimating the Due Date. American College of Obstetricians and Gynecologists, American Institute of Ultrasound in Medicine and Society for Maternal-Fetal Medicine. Obstetrics & Gynecology, vol. 129, no. 5, May 2017, pp. e150–e154. www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2017/05/methods-for-estimating-the-due-date
Khambalia, Amina Z., et al. “Predicting date of birth and examining the best time to date a pregnancy.” International Journal of Gynaecology and Obstetrics, vol. 123, no. 2, November 2013, pp. 105–109. pubmed.ncbi.nlm.nih.gov/23932061/
Committee Opinion No. 671: Perinatal Risks Associated With Assisted Reproductive Technology. American College of Obstetricians and Gynecologists, September 2016. www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2016/09/perinatal-risks-associated-with-assisted-reproductive-technology
Obstetric Care Consensus No. 6: Periviable Birth. American College of Obstetricians and Gynecologists and Society for Maternal-Fetal Medicine, October 2017. www.acog.org/clinical/clinical-guidance/obstetric-care-consensus/articles/2017/10/periviable-birth
Mancuso, Francesca, Manvinder Singh and Anthony L. Shanks. “In Vitro Fertilization.” StatPearls, StatPearls Publishing. www.ncbi.nlm.nih.gov/books/NBK562266/
Committee Opinion No. 579: Definition of Term Pregnancy. American College of Obstetricians and Gynecologists. Obstetrics & Gynecology, vol. 122, no. 5, November 2013, pp. 1139–1140. www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2013/11/definition-of-term-pregnancy
Medically reviewed by
Retired, board-certified obstetrician–gynecologist with nineteen years of clinical practice, trained at The Ohio State University. She reviews the calculation method and the clinical explanations on this site. Read full bio →
This calculator gives an estimate, not medical advice. A due date describes a likely window rather than a scheduled arrival, and your clinic or obstetrician may date your pregnancy slightly differently after a scan. Always confirm your dates with the team looking after you. Read the full medical disclaimer →
History of updates
8 September 2026 — current version
Evidence summary and primary-source reference list added. Medically reviewed by Kimberly Langdon, MD.
8 September 2026
Calculator, milestone calendar and initial guidance published.