Baby Due Month Calculator

Estimate your baby's due month using our simple due date calculator. Simply enter your last menstrual period date to get an estimated delivery date. This calculator uses standard pregnancy duration assumptions to provide a quick estimate.

How to Use This Calculator

Using our baby due month calculator is straightforward:

Enter the date of your last menstrual period (LMP) in the calculator form.
Click the "Calculate" button to get your estimated due date.
Review the result which shows your due month and week.
Use the chart to visualize your pregnancy timeline.

The calculator uses standard pregnancy assumptions of 40 weeks (280 days) from the first day of your last menstrual period.

How the Due Date Calculation Works

The due date calculation is based on standard pregnancy assumptions:

Formula

Due Date = Last Menstrual Period + 280 days (40 weeks)

This formula accounts for the average length of a full-term pregnancy.

Pregnancy duration varies naturally, so the actual delivery date may differ by a few weeks from the estimated date.

Example Calculation

If your last menstrual period was on January 1, 2023:

Example

January 1, 2023 + 280 days = October 28, 2023

This would be your estimated due date, with October being your due month.

Remember that actual delivery dates can vary by several weeks from this estimate.

Important Notes About Due Dates

While our calculator provides a useful estimate, remember these important points:

Pregnancy duration varies naturally between 37 and 42 weeks
Your due date is an estimate, not a guaranteed delivery date
Medical professionals may adjust the due date based on ultrasound measurements
Some pregnancies progress faster or slower than average

For the most accurate information, consult with your healthcare provider.

Frequently Asked Questions

How accurate is the due date calculator?: The calculator provides a reasonable estimate based on average pregnancy duration. Actual delivery dates may vary by several weeks.
Can I use this calculator for multiple pregnancies?: Yes, you can use the calculator for each pregnancy by entering the appropriate last menstrual period date.
What if I don't know my exact last menstrual period date?: Use your best estimate of the first day of your last menstrual period. The calculator will still provide a useful estimate.
How does the calculator handle leap years?: The calculator automatically accounts for leap years in the date calculations.
Is the due date the same as the due month?: Yes, the due month is simply the month component of your estimated due date.