Due Date Calculator

Calculate your Due Date

If you know that you’re pregnant, you probably want to be the first to know when your baby is going to be born.

Only 4% of women actually give birth on the due date. Still, it’s nice to know around which date you meet your baby! With this tool, you will find out when that will approximately be!

When is my due date?

The due date tells you when you expect to give birth to your baby. In most cases, you will give birth +/- 3 weeks before and 2 weeks after the determined due date. Knowing the due date is not only important for you, but also for the midwives. This way they can keep an eye on whether your baby is developing properly. The due date is usually 40 weeks from the first day of your last period. 

Outside the womb, your baby’s development continues. Did you know that our app ‘The Wonder Weeks’ describes the (mental) development of your baby in the first 20 months of his/her life? Full of tips and insights!

How long am I pregnant in relation to the due date?

There can still be some confusion about how long you are pregnant. How long you are pregnant depends on when you start counting. If you start counting from the moment of conception, you are 38 weeks pregnant. If you start counting from the first day of your last period, you are 40 weeks pregnant.

How is my due date calculated?

You may be wondering how it is possible that the number of weeks differs. Because you can never find out exactly when the moment of conception is, the first day of your last period is used to calculate as accurately as possible when your baby will be born. It takes approximately 38 weeks from the moment of conception to a full-term baby.

So, do you want to know when your baby will be born approximately? Take the first day of your last period and add 40 weeks (280 days). Keep in mind that this remains an indication and that it is most reliable with a regular cycle. 

The date of your ovulation depends on the length of your cycle. Your due date will be further away in pregnancy with a longer cycle than with a shorter one. Every day that your cycle lasts longer than 28 days, the due date will be one day later. And the other way around, every day that your cycle lasts shorter than 28 days, the due date will be one day earlier.

Is the due date from this tool reliable?

The due date is a good indication of when you will give birth. With a regular cycle of 28 days, this tool is reliable. Still, it remains an indication and the midwife will determine the official due date. 

A few situations that may affect the outcome of the tool:

• You were still on a contraceptive pill (up to 3 months ago)
• An irregular cycle
• A menstrual cycle that is much longer or shorter than 28 days

Facts about the due date 

• Only 4% of women actually give birth on the due date. Still, it is a good indicator to keep track of a baby’s development.
• In about 40% of pregnant women, the “add 280 days to the first day of the last menstrual period” method is not reliable. The main reason is an irregular menstrual cycle or that it is not entirely clear when the first day of the last menstruation was.
• The due date can also be calculated at the 12/13/14 week term ultrasound on the basis of the head circumference and the length of the baby. After 14 weeks this is no longer possible because every baby grows differently. 
• Over 90% of all babies are born between 3 weeks before and 2 weeks after the due date. Which makes an average pregnancy last between 37 and 42 weeks.