🤰 Pregnancy Due Date Calculator

Calculate your estimated due date (EDD) from your last menstrual period, conception date, or ultrasound date.

Calculation Method

Estimated Due Date
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Current Week
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Trimester
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Days Until Due
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Conception (est.)
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End of 1st Trimester
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End of 2nd Trimester
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How Due Date Is Calculated

The standard Naegele's Rule: add 280 days (40 weeks) to the first day of the last menstrual period. This assumes a 28-day cycle; the calculator adjusts for longer or shorter cycles.

EDD = LMP + 280 days + (cycle length − 28) days

Trimester Timeline

  • 1st Trimester: Weeks 1–13 (organ development, highest miscarriage risk)
  • 2nd Trimester: Weeks 14–27 (growth, movement begins)
  • 3rd Trimester: Weeks 28–40 (rapid growth, birth preparation)
How accurate is the due date? +
Only about 5% of babies are born on their exact due date. Most are born within 2 weeks before or after. Early ultrasound (before 13 weeks) provides the most accurate dating. The due date is an estimate — full term is 39–40 weeks, and anything from 37–42 weeks is considered normal.