Pregnancy Due Date Calculator: Estimate Your Baby's Arrival

Finding out your estimated due date is one of the most exciting milestones of pregnancy. Our Pregnancy Due Date Calculator estimates your due date based on the first day of your last menstrual period (LMP) or your conception date. While only 5% of babies arrive exactly on their due date, knowing the estimated window helps you prepare for your baby's arrival and track your pregnancy progress week by week.

How Due Dates Are Calculated

The standard method uses Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period. This assumes a 28-day cycle with ovulation occurring on day 14. If you know your conception date or ovulation date, the calculator adds 266 days (38 weeks) from that date.

Due dates are estimates based on averages. Gestation is considered full-term at 39-40 weeks, early-term at 37-38 weeks, and late-term at 41 weeks. Babies born between 37 and 42 weeks are generally considered healthy.

Using the Due Date Calculator

Enter the first day of your last menstrual period and your average cycle length (if not 28 days). The calculator shows your estimated due date, current gestational age in weeks and days, and the trimester you are in. You can also enter a conception date if known for a more precise estimate.

The calculator also shows important milestones: when the heart starts beating (week 6), when organs develop (weeks 8-12), when movement is felt (weeks 16-22), and when the baby is considered viable (week 24).

Pregnancy Timeline

First Trimester (Weeks 1-12)

Major organ development occurs. Common symptoms include morning sickness, fatigue, and breast tenderness. Most miscarriages occur during this period. Prenatal vitamins with folic acid are essential during these weeks to prevent neural tube defects.

Second Trimester (Weeks 13-26)

Morning sickness typically subsides. The baby begins to move, and the belly becomes visibly pregnant. Anatomy scan (ultrasound) is performed around week 20 to check development and often reveal the baby's sex. Many women find this trimester the most comfortable.

Third Trimester (Weeks 27-40)

The baby gains weight rapidly and organs mature. Common symptoms include back pain, Braxton-Hicks contractions, and frequent urination. The baby usually settles into a head-down position around week 34-36. Preparation for labor and delivery intensifies during this period.

Factors Affecting Due Date Accuracy

• Cycle length: Women with longer or shorter cycles ovulate at different times. The calculator adjusts for your cycle length to improve accuracy.
• First-trimester ultrasound: The most accurate method for dating a pregnancy. Ultrasound measurement of the crown-rump length between weeks 8-13 can estimate due date within 5-7 days.
• Irregular cycles: Women with irregular periods may have less accurate LMP-based estimates. Ultrasound dating is strongly recommended in these cases.
• Multiple pregnancies: Twins and triplets often arrive earlier than singletons. The average gestational age for twins is 36 weeks and for triplets is 32 weeks.

Preparing for Your Due Date

Use your estimated due date to plan maternity leave, prepare the nursery, and schedule prenatal appointments. However, keep in mind that due dates are estimates — pack your hospital bag by week 36, and consider that your baby may arrive any time between weeks 37 and 42. Talk to your healthcare provider about signs of labor and when to go to the hospital.

Start Calculating

Use our Pregnancy Due Date Calculator below to estimate your baby's arrival date and track your pregnancy progress. Also check our Ovulation Calculator for family planning and our Age Calculator to calculate your baby's age after birth.