Pregnancy due date calculator
Want to know when your baby is due? Use our pregnancy calculator to work out how many weeks pregnant you are and the due date to mark in your calendar.
Calculate your baby's due date
Using the first day of your last period, and your average menstrual cycle (this is the number of days from the start of one period to the day before the next one), it's possible to estimate the date you conceived. Pregnancy is counted as being 40 weeks long, so your due date is calculated at 280 days from conception. Don't worry – our tool will do those sums for you, just fill in your info below and the results will show on our due date calendar.
So you're having a baby (hurrah!) but when exactly? Early pregnancy isn't the time to be wrestling with calendars, charts and menstrual cycles - you've quite enough to make you feel queasy already. Simply enter your details in our pregnancy due date calculator and we'll do the rest.
Enter the date your last period started
How accurate are due dates?
At your 12-week scan (which can happen any time between 10 and 14 weeks), an ultrasound will be used to measure your baby and determine the stage of pregnancy you're at. Your due date will then be confirmed with greater accuracy.
Remember, a due date is not a definite birth date, more a rough estimate at this stage. In fact, fewer than 5% of babies are born on their actual due date, but at least it gives you a rough deadline for buying the pushchair / painting the nursery / choosing a name.
How many weeks pregnant are you?
Based on the date your baby is due and/or the first day of your last period, you can count the number of weeks to see how pregnant you are. Once you know the magic number, find out what you can expect in the weeks ahead, using our pregnancy calendar.
Keep track of how your baby is developing week by week, the changes happening to your body and what appointments you'll have, as well as looking ahead to giving birth and life with a newborn (we know that part seems a long way off right now). In the meantime, chat with other mums-to-be who are at the same stage as you, by joining a Mumsnet antenatal club.