First Day of Last Period (LMP)

Cycle Length

— OR IF YOU KNOW CONCEPTION DATE —

Conception Date

Estimated Due Date

Week
Days Left

📅 Your Personal Medical Roadmap

Fetal Development

Size Comparison

Length:
Weight:

Calculation Methodology

This tool employs a modified version of Naegele’s Rule. Standard calculators assume a 28-day cycle, often resulting in a margin of error of +/- 5 days. Our algorithm adjusts the Estimated Due Date (EDD) by factoring in cycle length variations using the formula: LMP + 280 days + (Cycle Length - 28). This aligns with clinical dating protocols used before the first-trimester ultrasound.

Clinical Milestones Reference

The timeline generated above estimates critical screening windows based on ACOG (American College of Obstetricians and Gynecologists) guidelines:

Weeks 11–13: Nuchal Translucency (NT) Scan window.
Weeks 18–22: Anatomy Scan (Level 2 Ultrasound) for structural assessment.
Weeks 24–28: Glucose Challenge Screening for gestational diabetes.

Medical Disclaimer: This tool is for informational purposes only and does not constitute medical advice. The most accurate dating method remains a crown-rump length (CRL) measurement via ultrasound in the first trimester.