Health
Pregnancy Due Date Calculator
Your estimated due date and current week of pregnancy, based on your last menstrual period.
Estimated due date
—
Enter the first day of your last period
Estimated using Naegele's rule (280 days from your last period) — a standard estimate, not a diagnosis. Actual due dates vary; your doctor's ultrasound-based estimate is more accurate.
Frequently asked questions
How is the due date calculated?
Using Naegele's rule — adding 280 days (40 weeks) to the first day of your last menstrual period. It's a standard estimate used widely in obstetrics, though only a small percentage of babies arrive exactly on their estimated due date.
How many weeks pregnant am I?
The calculator shows this automatically based on the number of days since your last period, once you enter the date.
Is this as accurate as a doctor's estimate?
It's a reasonable starting estimate, but an early ultrasound is generally considered more accurate for confirming gestational age, especially if your cycle is irregular.