Pregnancy due date calculator

Congratulations! Use our simple pregnancy due date calculator to help predict what day your baby may arrive and how many weeks pregnant you are

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When is your baby due? To find out, input the first day of your last period, and the average length of your menstrual cycle (if you’re not sure, it will input 28 days) into our due date calculator right here.

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Due date calculator

How does the due date calculator work?

Generally, you ovulate 2 weeks after the first day of your period, and will conceive shortly after that.

The average pregnancy lasts between 37 and 42 weeks, so it is possible to give a due date based on all of this information – though there will probably be a bit of wriggle room on either side.

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How likely is it my baby will arrive on my due date?

Actually – it’s not very likely that they’ll arrive dead on the actual predicted due date. Data from the Perinatal Institute suggests only 4% of babies arrive on the exact day predicted.

And anecdotal evidence from our Facebook community  backs this up. Debbie H says:

“First born 6 days late, 2nd born 1 day early, 3rd born 2 weeks early, 4th born 1 day late!”

Though – that’s not always the case. A few of our mums, like Natasha B, had very punctual babies: “All 3 of mine came on their due date x.”

If you’ve been tracking your pregnancy efforts closely – perhaps using a tool like our ovulation calendar – you might be able to pinpoint a day when you reckon there’s a good chance you conceived (most likely, a day around ovulation, when you had sex).

And, believe it or not, some women do say they just knew the moment they were pregnant (read those stories here) – in which case, if you pass this onto your doctor or midwife, they may well be able to give you a more accurate due date than without having this info. 

Is your first baby more likely to be late?

According to some studies, yes, firstborns are more likely to be late. A 2002 study of 9,148 live births in the USA did find a slightly higher incidence of first babies being born at 41 weeks or later – in fact, first babies have a 15-16% chance of being born early as opposed to a 9-10% chance with other babies.

However – don’t bank on this happening, as plenty of mums have experienced having early first babies, too. In our Facebook community, Kate M says: “My first was born 37+3. Massive shock I was so unprepared and thought I had ages. Thank God for 24hr Asda

And MFM team mum Tara B reveals: “I finished work on Friday, expecting to have 3 weeks off before my first and only baby was born. But my waters broke on the Saturday and I had her on the Sunday. We didn’t even have a bed for her!”

Will my due date change after a scan? 

Possibly, yes. On our forum, mum AbnormalKitty says: “I had an early scan at 8 weeks, which put me back a week. Then at my 12-week scan, they put me forward by 4 days.” 

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Your 12-week scan is also known as your dating scan. As well as checking your baby is growing healthily it will also be used to try and give a due date, known as an EDD (an estimated due date (and the ‘estimated’ is quite important here!)

Bearing all this in mind, though, we reckon it’s still pretty handy to have a due date noted  – as, even if your baby doesn’t come right on time, it gives you something to work towards as you go through your pregnancy. 

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