Pregnancy Due Date Calculator

How do you want to calculate your due date?
Enter the first day of your last period
What is your average cycle length?
Enter your due date
Please note that the Women's Health Tracker does not collect, save, or process any information you enter into these free online tools. All the information entered here strictly stays in the browser session and will get lost once you close the browser.

Using the pregnancy due date calculator

Using the pregnancy due date calculator is very simple. Simply select one of the two methods that you want to use to calculate your due date. The first method is the "Last Menstrual Period" or LMP method. In this method, you need to enter the first day of your last period and your average period or cycle length. The second method is the "Conception Date" method. Use this if you already know the date you conceived.

After entering the correct dates and optionally selecting the period length in the LMP method, click on the "Calculate my due date" button. The online tool will then calculate your expected delivery date and also show you where in the pregnancy stage you are today.

How does Women's Health Tracker calculate my due date?

Depending on the method you are using in the tool, here is how the calculations are done.

Due Date by Last Menstrual Period

In this method, the due date is calculated by adding 280 days or 9 months (the usual length of a normal pregnancy) to the first day of the last menstrual period. Note, that the actual due date may be before or earlier than the predicted date. This is because the above calculation is done based on a standard average period length of 28 days. The tool does account for non-standard period lengths but it may not be always accurate.

Due Date by Conception Date

In this method, 266 days are added to the date of your conception or ovulation. This method also relies on how accurate your date of conception is.

You already know your due date

In this method, you simply enter the due date that is given to you by your health care provider, and then you can use the online tool to track your week-by-week pregnancy progress.

What can cause the due date to change?

It is possible for the due date to change especially if you have a very irregular menstrual cycle length as that makes predicting the exact due date that much harder. If you are working with your healthcare provider then he/she might update your due date after monitoring the baby development on a regular basis throughout your pregnancy.

What are the chances of me giving birth on my due date?

Our due date calculator gives you an approximate date on which you can give birth. This is of course not 100% accurate as the exact due date depends on a lot of factors including how your pregnancy is progressing amongst other factors. In general, less than 5% of women deliver on their due date. It is very common to have a delivery two weeks before or after the expected due date.
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