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Baby Calculator Due Date Week Week

Reviewed by Calculator Editorial Team

Tracking your baby's due date by week can help you monitor pregnancy progress and prepare for the arrival of your little one. This calculator helps you determine the estimated due date based on your last menstrual period (LMP) or ultrasound date.

How to Use This Calculator

To calculate your baby's due date by week:

  1. Enter your last menstrual period (LMP) date or ultrasound date.
  2. Select whether you're using LMP or ultrasound date.
  3. Click "Calculate" to see your estimated due date and current pregnancy week.

The calculator will display your estimated due date and show your current pregnancy week on a chart.

Formula Used

The standard pregnancy duration is 40 weeks (280 days). The due date is calculated as:

Due Date = LMP Date + 280 days or Due Date = Ultrasound Date + (280 - (Ultrasound Week × 7)) days

Current pregnancy week is calculated as:

Current Week = (Days Since LMP or Ultrasound) ÷ 7

Note: This calculator uses the standard 40-week pregnancy duration. Individual pregnancies may vary.

Worked Example

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

  1. Enter January 1, 2023 as your LMP date.
  2. Select "LMP Date".
  3. Click "Calculate".

The calculator will show:

  • Estimated due date: October 31, 2023 (280 days after January 1, 2023).
  • Current pregnancy week: Week 1 (assuming today is January 1, 2023).

If you had an ultrasound on February 1, 2023 showing your baby is 12 weeks old:

  1. Enter February 1, 2023 as your ultrasound date.
  2. Select "Ultrasound Date".
  3. Click "Calculate".

The calculator will show:

  • Estimated due date: October 31, 2023 (280 days after February 1, 2023 minus 84 days for the 12 weeks).
  • Current pregnancy week: Week 12.

Interpreting Results

The estimated due date is based on the standard 40-week pregnancy duration. Keep in mind that:

  • Individual pregnancies may vary.
  • Ultrasound dates are more accurate than LMP dates.
  • Your healthcare provider may adjust the due date based on your specific situation.

Use this calculator to track your pregnancy progress and prepare for your baby's arrival.

FAQ

How accurate is this calculator?
The calculator provides an estimate based on standard pregnancy duration. For precise due dates, consult your healthcare provider.
Can I use this calculator for multiple pregnancies?
Yes, you can use the calculator for each pregnancy separately by entering the appropriate dates.
What if my pregnancy is high-risk?
High-risk pregnancies may have different due dates. Always follow your healthcare provider's advice.
How do I know if my ultrasound date is accurate?
Ultrasound dates are generally more accurate than LMP dates. Your healthcare provider can confirm the accuracy.
Can I save my pregnancy progress?
This calculator does not save data. For tracking purposes, consider using a pregnancy journal or app.