Babycenter Baby Due Date Calculator

Pregnancy is a special time, and knowing your baby's due date helps you plan for the arrival. Our BabyCenter Baby Due Date Calculator provides an estimated due date based on your last menstrual period (LMP) or ultrasound date. This tool is designed to help you track your pregnancy journey with accuracy.

How to Use This Calculator

Using our due date calculator is simple. You'll need either:

Your first day of your last menstrual period (LMP)
Your ultrasound date and the estimated gestational age at that time

Enter the relevant information into the calculator, and it will provide you with an estimated due date. The calculator uses standard pregnancy duration of 40 weeks (280 days) from conception.

Note: This calculator provides an estimate. Actual due dates may vary by a few days due to individual differences in pregnancy length.

How the Due Date Calculation Works

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

If you know your last menstrual period (LMP): Add 280 days (40 weeks) to your LMP date.
If you have an ultrasound date: Add the number of days remaining in your pregnancy based on your gestational age at the ultrasound.

Due Date = LMP Date + 280 days
Or
Due Date = Ultrasound Date + (280 days - Gestational Age at Ultrasound)

For example, if your LMP was January 1, 2023, your estimated due date would be October 9, 2023 (280 days later).

Example Calculation

Scenario

You had your last menstrual period on March 15, 2023.

Calculation

Adding 280 days to March 15, 2023:

March has 31 days (15 + 16 = 31)
April has 30 days (31 - 31 = 0, so we're at April 1)
May has 31 days (1 + 31 = 32)
June has 30 days (32 - 30 = 2)
July has 31 days (2 + 31 = 33)
August has 31 days (33 - 31 = 2)
September has 30 days (2 + 30 = 32)
October has 31 days (32 - 30 = 2)

Final due date: October 2, 2023

Pregnancy Milestones

Tracking pregnancy milestones helps you understand your baby's development. Here are some key stages:

Week	Milestone
1-4	Implantation and early development
5-8	Major organs forming
9-12	Limbs and facial features developing
13-16	Baby can hear and move
17-20	Eyes and hair are forming
21-24	Baby can taste and swallow
25-28	Lungs and digestive system developing
29-32	Baby gains weight rapidly
33-36	Baby is fully developed
37-40	Final growth and preparation for birth

Frequently Asked Questions

How accurate is the due date calculator?: The calculator provides an estimate based on average pregnancy length. Actual due dates may vary by a few days due to individual differences.
Can I use this calculator if I had an ultrasound?: Yes, you can enter your ultrasound date and the estimated gestational age to get a more precise due date.
What if I don't know my last menstrual period?: If you don't know your LMP, you can use the ultrasound method by entering your ultrasound date and gestational age.
How do I know if my baby is on track?: Regular prenatal checkups with your healthcare provider can help monitor your baby's growth and development.
What should I do if my due date changes?: If your due date changes significantly, consult with your healthcare provider to discuss any potential concerns.