IVF Due Date Calculator guide
IVF Due Date Calculator: Due Date from Your Embryo Transfer
Use our IVF Due Date Calculator to work out your due date from a day 3, day 5 or day 6 embryo transfer, fresh or frozen, or from your egg collection date.
By the AllCalculator editorial teamUpdated 15 October 20263 min read
After IVF, you know something most pregnant people don't: exactly when your embryo was created. That makes an IVF due date one of the most accurate there is, as long as it's worked out the right way.
Our IVF Due Date Calculator uses your transfer date and the age of your embryo to give your due date, along with your key scan dates. For a pregnancy that wasn't through IVF, use our main Pregnancy Calculator instead.
How an IVF due date is calculated
A due date is about 266 days after fertilisation, which is the same as 280 days after the first day of a last period.
With IVF, the embryo is grown in the lab for a few days before it's transferred. So the calculation starts from the transfer date and takes off the embryo's age:
| Type of transfer | Days added to the transfer date |
|---|---|
| Day 3 embryo | 263 days |
| Day 5 embryo (blastocyst) | 261 days |
| Day 6 embryo | 260 days |
| Egg collection or IUI date | 266 days |
It doesn't matter whether the embryo was fresh or frozen. A frozen day 5 blastocyst is still 5 days old when it's transferred, so the same calculation applies.
How to use the calculator (IVF Due Date Calculator)
- Choose your type of treatment: a day 3, day 5 or day 6 transfer, or an egg collection or IUI date.
- Enter the date of your transfer, or your egg collection or IUI.
You'll see your estimated due date, how many weeks pregnant you are today, the equivalent last period date and a table of key dates, including your dating scan and anomaly scan windows.
A worked example
Say you had a day 5 blastocyst transfer on 6 April 2026:
- Fertilisation was 5 days earlier, on 1 April 2026
- Due date: 1 April 2026 + 266 days = 23 December 2026
- That's the same as 6 April + 261 days
If the same pregnancy were dated from the egg collection on 1 April, you'd get the same answer: 1 April + 266 days.
Why your clinic talks about an "equivalent" last period
Antenatal care in the UK is planned in weeks of pregnancy counted from the first day of a last period. For IVF pregnancies, clinics and midwives work out an equivalent date: 2 weeks before fertilisation. That's why you're already counted as about 4 weeks pregnant at the time of a typical pregnancy test, around 2 weeks after collection.
The calculator shows this equivalent date, so you can use our How Many Weeks Pregnant Calculator or Pregnancy Trimester Calculator with your due date too.
What happens next
After a positive test, most clinics offer an early scan at around 6 to 7 weeks. You'll then be referred to NHS maternity care like any other pregnancy, with a booking appointment, a dating scan at 10 to 14 weeks and an anomaly scan at 18 to 21 weeks.
Your dating scan may confirm your IVF due date or adjust it slightly. Your clinic or midwife will tell you which date to use.
Frequently asked questions
Is an IVF due date accurate?
It's one of the most accurate ways to date a pregnancy, because the date of fertilisation is known. Most babies still arrive between 37 and 42 weeks, so your due date is a guide rather than a deadline.
Do frozen embryo transfers use a different calculation?
No. What matters is the embryo's age when it was transferred, not whether it was frozen. A day 5 frozen embryo is dated the same as a day 5 fresh one.
How many weeks pregnant am I after a day 5 transfer?
On the day of a day 5 transfer, you're counted as 2 weeks and 5 days pregnant, because pregnancy is dated from an equivalent last period 2 weeks before fertilisation.
Are IVF twins due earlier?
The due date is calculated the same way, but twins are more likely to arrive early, and your care team may plan for an earlier birth.
Fertility treatment can be a long road, and seeing a due date can make it feel real. Use the IVF Due Date Calculator for your dates, and count down the days with our Pregnancy Countdown Calculator.
Sources and further reading
- NHS: IVFnhs.uk
- HFEA: In vitro fertilisation (IVF)hfea.gov.uk
- ACOG: Methods for estimating the due dateacog.org
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This guide is general information to help you understand your options. It isn't financial, tax, legal or building advice and doesn't take your personal circumstances into account. Figures were checked when the guide was last updated and can change, so confirm anything important with GOV.UK, HMRC, a regulated adviser or a qualified tradesperson.