IVF Due Date Calculator
IVF Pregnancies Don't Need to Guess
Standard due-date math relies on Naegele's rule dating from the last menstrual period, because ovulation timing is normally unknown and has to be estimated. IVF removes that uncertainty entirely: the embryo's exact age is known to the day at transfer, which makes IVF-derived due dates among the most precise available — no cycle-length correction or ovulation guesswork required.
The Formula
266 days is the length of a full-term pregnancy counted from fertilization (egg retrieval), which is 40 weeks from the last period minus the roughly two weeks between LMP and ovulation. Subtracting the embryo's age at transfer accounts for the days that have already passed since fertilization by the time it's placed in the uterus.
Day 3 vs. Day 5 Transfers
| Transfer type | Embryo age at transfer | Days added to transfer date |
|---|---|---|
| Day 3 (cleavage-stage) | 3 days | 263 days |
| Day 5 (blastocyst) | 5 days | 261 days |
The two-day gap between cleavage-stage and blastocyst transfer is simply the two additional days the embryo spent developing in the lab before transfer — the fertilization date itself doesn't change.
What Else This Calculates
Alongside the due date, this calculator derives the estimated retrieval/fertilization date (transfer date minus embryo age) and an equivalent LMP date (retrieval date minus 14 days), so the result can be cross-referenced against standard LMP-based pregnancy charts and week-by-week guides that assume LMP dating.
Where This Matters
- Scheduling around a confirmed due date — IVF timelines are known with unusual precision, making early planning more reliable than in a typical pregnancy.
- Reconciling with LMP-based tools — the equivalent LMP figure lets you use standard pregnancy week charts that assume a last-period start.
- Comparing transfer-day protocols — understanding exactly how a Day 3 versus Day 5 transfer decision shifts the projected due date.
How to Use This Calculator
- Enter the Embryo Transfer Date.
- Select Day 5 Transfer (Blastocyst) or Day 3 Transfer (Cleavage-stage).
- Select Calculate for the estimated due date, retrieval/fertilization date, equivalent LMP date, and current gestational age.
Related Calculations
For a version that also accepts natural-conception dating alongside IVF, see the Due Date Calculator. To track your current week and trimester as the pregnancy progresses, use the Pregnancy Week Calculator.