Pregnancy due date calculator
Estimate a due date from the first day of your last period. Private: it runs in your browser and nothing is sent to us.
How the estimate works
The standard method adds 280 days (40 weeks) to the first day of your last menstrual period, assuming a 28-day cycle. We adjust the date if your cycle is usually longer or shorter.
Only a small share of babies arrive on their exact due date. The American College of Obstetricians and Gynecologists notes that an early ultrasound can give a more accurate estimate, so your care team may change the date after your first scan.
This tool gives a general estimate and is not medical advice or a diagnosis.