Pregnancy Due Date Calculator

Find your baby’s due date from your last period, conception or IVF transfer date — with week-by-week milestones.

How is the due date calculated?

The due date is 280 days (40 weeks) after the first day of your last menstrual period, adjusted for cycles longer or shorter than 28 days (Naegele’s rule). From a known conception date it is 266 days later; after an IVF day-5 transfer, 261 days later.

What the result shows

Your estimated due date and how many days are left.
How far along you are today (weeks + days) and your trimester.
Dates of key milestones: the end of the first trimester (week 13), the anatomy scan (weeks 18–22), full term (week 39).

Only about 1 in 20 babies is born on the due date itself; most arrive between weeks 37 and 42. An early ultrasound can refine the date.

Frequently asked questions

How many weeks is a full-term pregnancy?

39 to 40 weeks; 37–38 weeks is early term.

Why count from the last period?

The exact conception date is rarely known, while the start of the last period usually is.

Can the due date change?

Yes, your doctor may update it after the dating scan.