Due Date Calculator

Congrats, you're pregnant! Use our simple MFM calculator to find out when your baby is due, as well as how many weeks you are into your pregnancy.

When was the first day of your last period?

How long does your cycle usually last?

Not sure?

We'll calculate this based on the average cycle length of 28 days

We must've made a mistake. Why not try refreshing the page to try again.

This is your estimated due date, but remember only around 4% of babies are born on their actual due date

Birth Club

Say hi, swap notes and meet others who are due in the same month as you.

Join the chat in our forum

Pregnant, trying to conceive or already a mum? Talk to others in our friendly community.

Try again

Take me to Chat


  • How do I measure the length of my cycle?

    Start date is: the day your period normally begins. Finish date is: the day before your next period starts. The average is 28 days, and if you're not sure or you're irregular, our calculator will use 28 days. However, cycle lengths can generally range from 21 to 35 days. Chances are, you won't have an exact length, but choose the one that's most common for you.

  • How accurate is this due date?

    This is your estimated due date (EDD) and the clue's in the title - it is just an estimate. Put simply, it's 40 weeks from your last menstrual period (LMP). Of course, cycle lengths and ovulation dates vary, so your EDD gives you a rough date that you can use to plan ahead, follow your baby's weekly development and meet other women due around the same time in our friendly Birth Clubs. You may get a more accurate due date if you have a dating scan at around 12 weeks.

  • How are my pregnancy weeks calculated?

    This is the confusing bit. Pregnancy weeks (like your due date) are measured from your last menstrual period (LMP), rather than when your egg is fertilised. This means that you're already about two weeks' pregnant when you conceive. Weird, huh? The reason for this is because your LMP is a fixed date and so it's easier to work from. Little known fact - when you're 40 weeks pregnant, your baby is actually only 38 weeks old!