When is my baby due?
A due date calculator for Ireland, with the dates that matter here.
In short
Your due date is usually 40 weeks (280 days) from the first day of your last period. Put in the date below and we will work out your due date, how far along you are and your key dates in Ireland.
- Works from your last period, conception, an IVF transfer or your dating scan.
- Shows the dating scan, anatomy scan, whooping cough vaccine and Maternity Benefit windows.
- Nothing you type here leaves your phone.
How is a due date worked out?
The HSE works out a due date as 40 weeks from the first day of your last period. That assumes a 28-day cycle with ovulation around day 14, so if your cycle is usually longer or shorter, the date moves by the difference. It also means that for the first 2 weeks or so of a pregnancy, you are not actually pregnant yet: the count starts before conception.
Does my dating scan change my due date?
It can. Every pregnant woman in Ireland is offered a dating scan, ideally before 15 weeks. Measuring your baby early on is the most accurate way to date a pregnancy, so if the scan and your period dates disagree, your maternity unit will usually go with the scan. Use the date your hospital gives you.
How do I work out my due date after IVF?
With IVF the date comes from the embryo, not your period: 261 days after a 5-day embryo transfer, or 263 days after a 3-day transfer. Your clinic will confirm it.
How likely is my baby to come on the due date?
Not very. Most babies arrive between 37 and 42 weeks, so treat your due date as the middle of a window. From 37 weeks your baby is full term. In a straightforward pregnancy in Ireland you are usually offered an induction at 41 weeks, after a full talk about the benefits and risks.
What happens next?
See your GP to confirm the pregnancy and register for free care under the Maternity and Infant Care Scheme. Then follow along week by week: what happens at each week of pregnancy, with the Irish dates that matter.
Questions and answers
How is a due date worked out in Ireland?
The HSE counts 40 weeks, or 280 days, from the first day of your last period, assuming a 28-day cycle. A longer or shorter cycle moves the date by the difference. Your dating scan, offered to everyone ideally before 15 weeks, may adjust it.
How do I work out my due date after IVF?
Use the embryo transfer date: add 261 days for a 5-day embryo (blastocyst) or 263 days for a 3-day embryo. Your clinic will confirm the date.
How accurate is my due date?
It is an estimate. Most babies arrive between 37 and 42 weeks, and only a small share arrive on the day itself, so it is more useful to think of a due month.
When is the dating scan and the anatomy scan?
The dating scan is offered ideally before 15 weeks, and the anatomy scan is usually between 18 and 22 weeks, depending on your maternity unit.
Sources and guidance
This page is written to be consistent with the official guidance below. It is general information for parents in Ireland, not medical advice. Links checked 23 September 2026.