Pregnancy Calculator

Calculate your due date, current pregnancy week, and track important milestones throughout your pregnancy journey.

Pregnancy Due Date Calculator

Choose your calculation method and enter the required information

Enter the first day of your last menstrual period. This is the most common method used by doctors.

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About Pregnancy Calculation

Most Accurate Methods

  • • Early ultrasound (6-12 weeks)
  • • Known conception date
  • • Regular menstrual cycles (LMP)

Important Notes

  • • Only 5% of babies are born on due date
  • • Full-term is 37-42 weeks
  • • Due dates can vary by ±2 weeks

Pregnancy Trimesters

1st Trimester

Weeks 1-12: Major organ development

2nd Trimester

Weeks 13-27: Often the easiest period

3rd Trimester

Weeks 28-40: Rapid growth and preparation

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Understanding Pregnancy Due Date Calculation

How Pregnancy is Calculated

Pregnancy is calculated from the first day of your last menstrual period (LMP), not from conception. This method assumes a 28-day cycle with ovulation occurring on day 14. A full-term pregnancy is 40 weeks or 280 days from LMP, which equals approximately 9 months and 1 week.

Calculation Methods

LMP Method: Due Date = LMP + 280 days (Naegele's Rule)

Conception Method: Due Date = Conception Date + 266 days

Ultrasound Method: Most accurate when performed between 6-12 weeks

Important Notes

Only about 5% of babies are born on their exact due date. Most babies are born within 2 weeks before or after the due date. The due date is an estimate to help track pregnancy progress and plan for delivery. Always consult your healthcare provider for accurate dating and medical advice.

Frequently Asked Questions

How accurate is the pregnancy due date calculator?

The pregnancy calculator is accurate to within a few days when based on the last menstrual period (LMP). However, only about 5% of babies are born on their exact due date, with most born within 2 weeks before or after. Early ultrasound dating is generally the most accurate method.

What's the difference between the calculation methods?

  • LMP Method: Uses the first day of your last menstrual period. Assumes a 28-day cycle with ovulation on day 14.
  • Conception Method: Uses the actual conception date, which is typically about 2 weeks after LMP.
  • Ultrasound Method: Uses measurements from an ultrasound scan. Most accurate when done between 6-12 weeks.

Can I use this calculator if I have irregular periods?

If you have irregular periods, the LMP method may be less accurate. Consider using the conception date method if you know when you conceived, or consult your healthcare provider for an ultrasound-based due date. Ovulation tracking or fertility treatments can provide more precise conception dates.

What are the important pregnancy milestones?

First Trimester

  • 6-8 weeks: Heartbeat detectable
  • 12 weeks: End of first trimester
  • 12 weeks: Decreased miscarriage risk

Second Trimester

  • 16 weeks: Gender often visible
  • 18-20 weeks: Anatomy scan
  • 20 weeks: Halfway point

Third Trimester

  • 24 weeks: Viability milestone
  • 28 weeks: Third trimester begins
  • 37 weeks: Full-term

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Medical Disclaimer

This pregnancy calculator provides estimates only and should not be used as a substitute for professional medical advice. Due dates are estimates and only about 5% of babies are born on their exact due date. Please consult your healthcare provider for accurate pregnancy dating, monitoring, and medical advice throughout your pregnancy journey.