IVF Due Date Calculator
Calculate your due date precisely from embryo transfer or egg retrieval date, supporting Day 3, Day 5, Day 6 blastocyst transfer
Embryo type
Estimated due date
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Gestational age today
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Days to go
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Pregnancy milestones
First ultrasound
Confirms intrauterine pregnancy and heartbeat, 8–10 weeks
NT scan (first-trimester screening)
Nuchal translucency screening, 11–13+6 weeks
Mid-trimester screening
Serum marker screening for Down syndrome, 15–20 weeks
Anatomy scan
Systematic fetal structure survey, 18–24 weeks
Glucose tolerance test (OGTT)
Gestational diabetes screening, 24–28 weeks
Third-trimester visits begin
Biweekly checkups; start counting fetal movement
Late growth ultrasound
Assesses fetal weight, amniotic fluid and position
GBS screening + weekly visits
Group B strep test; prepare for labor
Suggested transfer date
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Embryo type
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Days from today
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Tip: prepare your body before transfer — keep a regular routine and a balanced diet.
Due date = transfer date + days (D3: +263, D5: +261, D6: +260)
How does this calculator work?
- 1 Enter your embryo transfer date
- 2 Select the embryo type (Day 3 cleavage, Day 5 blastocyst, or Day 6 blastocyst)
- 3 Get your estimated due date, current gestational age, and days remaining automatically
What Is an IVF Due Date?
An IVF due date = transfer date + offset days (Day 5 blastocyst +261, Day 3 +263, Day 6 +260). This is the most accurate dating method in obstetrics, with an error margin of only ±1–2 days. By comparison, natural pregnancies dated by last menstrual period (LMP) plus 280 days can be off by up to ±14 days.
Day 5 blastocyst transfer is the most common scenario: due date = transfer date + 261 days (37 weeks and 2 days). Day 3 cleavage-stage transfers use 263 days and Day 6 blastocysts use 260 days. These formulas apply to all transfers, including fresh and frozen (FET) cycles.
The reasoning behind the formula: the standard 40-week count of a natural pregnancy includes roughly two pre-conception weeks (from LMP to ovulation), so true gestation from conception to birth is 266 days (38 weeks). IVF simply subtracts the days the embryo was cultured: Day 5 blastocyst 266−5=261; Day 3 embryo 266−3=263; Day 6 blastocyst 266−6=260.
Once set, an IVF due date rarely changes, because the starting point is a known biological event. Only about 5% of babies are born on their due date; most arrive between weeks 37 and 42. Plan to be ready from week 37 onward.
How Is an IVF Due Date Calculated?
IVF due date formula: a Day 5 blastocyst transfer date plus 261 days (37 weeks and 2 days), a Day 3 cleavage-stage transfer plus 263 days (37 weeks and 4 days), and a Day 6 blastocyst transfer plus 260 days (37 weeks and 1 day). The logic: a natural pregnancy runs about 266 days from conception to birth, so IVF simply subtracts the days the embryo was cultured in the lab.
Transfer date + offset days = due date What Should I Know About IVF Due Date Calculation?
- • IVF due dates are more precise than natural-conception dates because the fertilization date is known exactly
- • Actual delivery may occur up to 2 weeks before or after the due date
- • Plan to be ready for labor from week 37 onward
Frequently Asked Questions
Why is an IVF due date more accurate than a natural one?
Does the calculation differ between blastocyst and Day 3 transfers?
How is the due date calculated for a frozen embryo transfer (FET)?
What if I don’t remember my transfer date?
References
- [1] ACOG recommends using the exact fertilization date to date IVF pregnancies, since that date is precisely known — ACOG Practice Bulletin #217
- [2] NICE fertility guideline NG201 confirms the IVF due-date method, recommending the transfer or retrieval date as the starting point — NICE Fertility Guideline NG201
- [3] Mayo Clinic notes that only about 5% of pregnant people deliver on their exact due date; most deliver between weeks 37 and 42 — Mayo Clinic - Pregnancy Due Dates
- [4] ASRM confirms IVF due dates are more precise than natural conception dating, with an error margin of just ±1–2 days — ASRM - Guidelines for Determining the Estimated Date of Delivery
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