Due Date Calculator - Free Online Tool | PivaBox

Estimate your pregnancy due date based on last menstrual period, conception date, or ultrasound date

How to Use Due Date Calculator

1. Select your date method — Last Menstrual Period (LMP), Conception Date, or Ultrasound Date
2. Enter the date and adjust your cycle length if different from the default 28 days
3. Click Calculate Due Date to see your estimated due date, current pregnancy week, trimester, and key milestones timeline

Frequently Asked Questions

Is Due Date Calculator free?

Yes, PivaBox Due Date Calculator is completely free to use. All calculations happen locally in your browser.

How is the due date calculated?

The calculator uses <strong>Naegele's Rule</strong>: Estimated Due Date = Last Menstrual Period + 280 days (40 weeks). For different cycle lengths, it adjusts by (cycle length - 28) days. This is the same method used by obstetricians worldwide.

How accurate is the due date?

Only about 5% of babies are born on their exact due date. The due date is an estimate — most babies arrive within 2 weeks before or after. Always consult your healthcare provider for personalized medical advice.