DUE DATE CALCULATOR

Calculate Your Due Date

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Online Pregnancy Calculator

Congratulations, you’re pregnant! 

Our Due Date Calculator is here to help you estimate when your little one will be arriving. Most pregnancies last about 40 weeks, so you can get an idea of your due date by counting 40 weeks, or 280 days, from your last menstrual period (LMP). You can also subtract 3 months from the date your last period began, then add 7 days. Or instead of all the counting, enter the date of your LMP into the calculator above! 

Once you enter the date of your last menstrual period, the calculator will tell you your estimated Conception Date (when you actually got pregnant) and your estimated Due Date. 

Remember, these are just estimations based on a 28-day menstrual cycle. If your cycle is irregular then it will be more difficult to estimate your Due Date using dates alone. You’ll receive a much more accurate Estimated Due Date (EDD) when you have a scan. 

If you can’t wait to find out your EDD, visit us in UltraScan where we perform Early Pregnancy Scans (or Dating Scans) from just 8 weeks. 

 

Can an Early Pregnancy Scan determine my due date?

Yes, our Early Pregnancy Scans are also referred to as Dating Scans for this reason. We use your baby’s measurements, in conjunction with the date of your last menstrual period to give you an estimated due date. Our estimated due dates are generally within 3 – 5 days of accuracy when measured during the first 12 weeks of pregnancy. 

Read more about our Early Pregnancy Scans, or make a booking.

 

Can my due date change?

It’s common for your estimated due date to be changed as your pregnancy progresses. Reasons for this may include not knowing the actual date of your last menstrual period, irregular periods or having your first scan in the second trimester.

 

Why is my pregnancy measured from my last period?

Most healthcare providers will estimate your baby’s due date based on the date you started your last period rather than the date you conceived for many reasons:

  1. Many women don’t know the date they conceived. If you were actively trying for a baby then you may have had unprotected sex every second day throughout the month. It’s impossible to know which occasion was successful. 
  2. Your menstrual cycle doesn’t work like clockwork. In theory, your cycle is 28 days long with ovulation occurring on day 14. However, this is a natural process so the actual day ovulation occurs can vary.
  3. Conception may not have happened on the day you had sex. Sperm can live inside your body for up to 5 days and the egg can survive for up to 24 hours after being released. 
 

With these reasons in mind, healthcare providers use your last menstrual period (LMP) as this is a definite date. So most pregnancies last 40 weeks or approximately 38 weeks from conception. 

 

Will my baby be born on their due date?

Only 5% of babies are born on their due date, so don’t put too much emphasis on this exact day. Look at it as a guide for when you should be ready for your baby to be born. Aim to have your labour bags packed and everything set up by 36 weeks just to be safe. 

 

Calculating the perfect time to get pregnant

There are many reasons why you might like to plan what month your baby will be born, such as work commitments or working around your other children. This is when it can be helpful to use an app like Flo or Natural Cycles to map your periods and ovulation. After a few months of inputting data, these apps can predict when your period will start each month and you can use this date to determine your theoretical due date. For example, if you want a June baby you will need to get pregnant in September. Look at your predicted period for September, then input that date into the calculator above to see your predicted due date.

It’s an exciting time for you, why not meet your little one in our relaxing baby scan suite?

Our Early Pregnancy Scan is a great way to settle your mind in the early days of your pregnancy. We can confirm how far along you are, the viability of your pregnancy and your Due Date. We calculate an accurate due date based on your baby’s size.