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Calculate your pregnancy due date based on your last menstrual period (LMP) or conception date. See your current week, trimester, and key milestones.
A pregnancy due date is the estimated date of delivery, calculated as 280 days (40 weeks) from the first day of the last menstrual period (LMP) or 266 days from conception using Naegele's rule.
The first day of your last menstrual period
Select a date to calculate your due date
First sign of pregnancy for most women
Initial doctor appointment typically scheduled
Risk of miscarriage decreases significantly
Baby's sex may be visible on ultrasound
Detailed ultrasound to check baby's development
Baby has a chance of survival if born early
Final stretch of pregnancy
Baby is considered full term
Estimated delivery date
Due dates are calculated using Naegele's rule — the standard obstetric method.
Due Date = LMP + 280 days (40 weeks)
Due Date = Conception + 266 days (38 weeks)
Only about 5% of babies arrive on their exact due date. Most are born within two weeks before or after.
Note: This calculator provides an estimate only. Your actual due date may differ. Only about 5% of babies are born on their exact due date. Always consult with your healthcare provider for personalized prenatal care and accurate dating, especially if you have irregular periods.
Formula
EDD (LMP method) = LMP + 280 days | EDD (conception) = conception date + 266 daysEDD = Estimated Due Date — also called Estimated Date of Confinement (EDC)
LMP = Last Menstrual Period — first day of last period; standard clinical baseline
280 days = 40 weeks of gestation; conception typically occurs ~14 days after LMP
266 days = 38 weeks from conception — the actual fertilisation-to-birth duration
Worked Example
Due date for LMP of January 1
Did you know? Only about 5% of babies are born on their exact due date. Most births occur within 2 weeks before or after the EDD — the 'normal' term range is 37–42 weeks. Due dates are estimates based on population averages; ultrasound dating in the first trimester is the most accurate method.
Sources
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