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Pregnancy Due Date

Knowing your estimated due date (EDD) is the foundation of prenatal care — it determines your gestational week, prenatal screening timing, and when you'll likely meet your baby. Our calculator uses Naegele's rule (the standard method) from your last menstrual period, or works backwards from a known conception date or ultrasound gestational age.

Date d'accouchement estimée

Actuellement :
Trimestre :
Conception :
Jours restants :
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À propos de Pregnancy Due Date Calculator

Knowing your estimated due date (EDD) is the foundation of prenatal care — it determines your gestational week, prenatal screening timing, and when you'll likely meet your baby. Our calculator uses Naegele's rule (the standard method) from your last menstrual period, or works backwards from a known conception date or ultrasound gestational age.

Comment l'utiliser

  1. Enter the first day of your last menstrual period (LMP).
  2. Or enter a known conception date (subtract ~14 days from the LMP equivalent).
  3. See your estimated due date, current gestational week, and trimester.
  4. View key milestone dates: 12-week NT scan, 20-week anatomy scan, 37-week full term.

Formule et méthodologie

Naegele's Rule: EDD = LMP + 9 months + 7 days (= LMP + 280 days). For irregular cycles, adjust: EDD = LMP + 280 days + (cycle length − 28). Conception-based: EDD = Conception date + 266 days (38 weeks). Gestational age = current date − LMP (in weeks + days).

Cas d'usage courants

  • First prenatal appointment: confirming gestational age
  • Planning maternity/paternity leave around expected delivery
  • Scheduling trimester-specific screenings (NT scan, anatomy scan, glucose test)
  • Understanding post-dates pregnancy if past 40 weeks
  • IVF embryo transfer: calculating EDD from transfer date

Questions fréquentes

Only about 5% of babies are born on their exact EDD. The normal delivery window is 37–42 weeks; most births occur within 2 weeks of EDD. An ultrasound before 20 weeks is more accurate than LMP-based dating (within ±5–7 days vs ±2 weeks). After 20 weeks, ultrasound dating becomes less precise.
Gestational age counts from the last menstrual period (LMP), which is approximately 2 weeks before conception. Fetal age (embryonic age) counts from conception and is about 2 weeks less than gestational age. Doctors always use gestational age — so a "6-week pregnancy" means about 4 weeks since conception.

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