When Will My Baby Arrive Calculator

Pregnancy is an exciting time, and knowing your estimated due date can help you plan for the arrival of your baby. Our due date calculator makes it easy to estimate when you'll deliver based on your last menstrual period or ultrasound date.

How to Use This Calculator

Using our due date calculator is simple. You have two options for calculating your estimated due date:

Using your last menstrual period (LMP): Enter the first day of your last menstrual period. Our calculator will add 280 days to this date to estimate your due date.
Using an ultrasound date: If you've had an ultrasound, enter the date of the ultrasound and the gestational age in weeks. Our calculator will add the remaining weeks to the ultrasound date to estimate your due date.

After entering your information, click "Calculate" to see your estimated due date. You can also reset the calculator to start over.

Important Note

This calculator provides an estimate of your due date. Actual delivery dates can vary, and it's always a good idea to consult with your healthcare provider for personalized advice.

How the Due Date Calculation Works

The due date calculation is based on standard pregnancy guidelines. Here's how it works:

Formula Used

For last menstrual period (LMP) method:

Due Date = LMP Date + 280 days

For ultrasound method:

Due Date = Ultrasound Date + (40 weeks - Ultrasound Weeks)

The average length of a full-term pregnancy is 40 weeks (280 days). The calculator uses this standard to estimate your due date. Keep in mind that:

Pregnancies can vary in length from about 37 to 42 weeks.
Some babies may arrive earlier or later than the estimated date.
Healthcare providers may adjust the due date based on individual circumstances.

Examples of Due Date Calculations

Let's look at a couple of examples to see how the calculator works in practice.

Example 1: Using Last Menstrual Period

If your last menstrual period started on January 1, 2024, the calculator would add 280 days to this date:

Due Date = January 1, 2024 + 280 days = October 7, 2024

Example 2: Using Ultrasound Date

If you had an ultrasound on June 1, 2024, and your baby was 12 weeks old at that time, the calculator would calculate:

Due Date = June 1, 2024 + (40 weeks - 12 weeks) = June 1, 2024 + 28 weeks = December 22, 2024

Remember

These examples are for illustration purposes only. Actual due dates can vary based on individual circumstances.

Frequently Asked Questions

How accurate is the due date calculator?: The calculator provides an estimate based on standard pregnancy guidelines. Actual delivery dates can vary, so it's always best to consult with your healthcare provider for personalized advice.
Can I use this calculator if I'm pregnant with twins or multiples?: Yes, you can use the calculator, but keep in mind that multiple pregnancies may have different due dates for each baby. Consult with your healthcare provider for more accurate information.
What if I had an early or late ultrasound?: If your ultrasound was early or late, the calculator will still provide an estimate based on the gestational age at the time of the ultrasound. For the most accurate information, consult with your healthcare provider.
Can I use this calculator if I'm pregnant with a high-risk pregnancy?: Yes, you can use the calculator, but keep in mind that high-risk pregnancies may have different due dates. Always consult with your healthcare provider for personalized advice.
Is the due date calculator free to use?: Yes, our due date calculator is completely free to use. There are no hidden fees or subscriptions required.