How do you calculate a due date for a 6 day transfer?

Add 260 days to the transfer date — 266 days from conception minus the six days the blastocyst spent developing in the lab.

Is a day-6 blastocyst as good as a day-5?

Day-6 blastocysts are slightly slower to expand but are routinely transferred and result in healthy pregnancies. Grade matters more than the extra day, and many clinics report similar outcomes for good-quality day-6 embryos.

How many weeks pregnant am I on a day-6 transfer day?

You are counted as 2 weeks and 6 days pregnant on the day of transfer — one day further along than a day-5 transfer on the same date.

When is the beta hCG after a 6 day transfer?

Usually 9 to 10 days past transfer, one day earlier in the day count than for a day-5 transfer because the embryo is already a day older. Follow your clinic's date.

Does a day-6 transfer mean the embryo is behind?

It means the embryo reached the blastocyst stage a day later than average, which is common and does not by itself indicate a problem. Once the embryo is frozen or transferred, dating simply uses its age.

6 Day Transfer Due Date Calculator

Enter the date of your day-6 blastocyst transfer for your estimated due date, your gestational age today, and the usual beta hCG and scan dates that follow.

Embryo transfer date

Estimated due date

Monday, June 14, 2027

Transfer date + 260 days. On transfer day you are counted as 2w 6d pregnant. A day-6 transfer dates one day earlier than a day-5 transfer on the same date.

This is an estimate for information only — only about 1 in 20 babies arrive on their due date. Always confirm dates with your midwife or doctor.

What happens after a day-6 transfer

Typical timings for a transfer on Sunday, September 27, 2026. Your clinic's own schedule always takes priority.

Milestone	Day past transfer	Gestational age	Date
Transfer day	—	2w 6d	Sunday, September 27, 2026
Earliest reliable home test	9dp6dt	4w 1d	Tuesday, October 6, 2026
First beta hCG (typical)	10dp6dt	4w 2d	Wednesday, October 7, 2026
Second beta hCG (typical)	12dp6dt	4w 4d	Friday, October 9, 2026
First ultrasound (typical)	21dp6dt	5w 6d	Sunday, October 18, 2026

The day-6 formula

The due date is the transfer date plus 260 days: 266 days from conception, minus the six days the embryo had already grown before transfer.

Everything downstream shifts with it. Gestational age on transfer day is 2w 6d, and each later milestone lands one day earlier in the day count than the equivalent day-5 milestone.

Why some blastocysts are day-6

Embryos do not all expand on the same schedule. Some reach a fully expanded blastocyst on day 5, others on day 6, occasionally day 7. Labs grade and freeze whenever the embryo is ready rather than forcing a fixed timetable.

In a frozen cycle the extra day matters even less, because the embryo is thawed and transferred at whatever stage it was frozen. What the calculator needs is that stage — day 6 — not how the embryo got there.

Testing after a day-6 transfer

Counting is written as dp6dt. Because the embryo is a day older, hCG typically becomes detectable in blood around 4-6dp6dt and on a home test around 7-9dp6dt.

That one-day head start is real but small. If a test at 7dp6dt is negative, it is genuinely too early to conclude anything.

Comparing day-5 and day-6 dates

A day-5 and a day-6 blastocyst transferred on the same calendar date give due dates exactly one day apart. Neither pregnancy is longer; the embryos simply started from different points.

If your clinic quotes a date that differs by a day or two from this calculator, use theirs — some clinics count from egg retrieval and round gestational age differently.

Other transfer days

More IVF calculators

All IVF calculators & guides →