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Pregnancy Week Calculator

How It Works

This calculator uses Naegele's Rule, the standard medical formula for estimating pregnancy due dates:

  • Due Date = LMP + 280 days (40 weeks)
  • Trimester 1: Weeks 1-12
  • Trimester 2: Weeks 13-26
  • Trimester 3: Weeks 27-40

Important Notes

  • This is an estimate only. Your doctor may adjust the due date based on ultrasound measurements.
  • The calculation assumes a regular 28-day menstrual cycle.
  • Always consult your healthcare provider for accurate pregnancy assessment.