Due date calculator

The standard obstetric estimate: 280 days from the first day of your last period (Naegele’s rule), adjusted for cycle length, with the key pregnancy milestones mapped out.

How to Due date calculator

1. Step 1. Pick the date you know: LMP, conception, or ultrasound.
2. Step 2. Enter the date and average cycle length.
3. Step 3. Review the estimated due date and days remaining.
4. Step 4. Read the milestone timeline: trimesters, anatomy scan, full term.

Frequently asked questions

What is Naegele’s rule?

Add 280 days (40 weeks) to the first day of the last menstrual period — the standard clinical due-date estimate used worldwide.

What does “full term” mean?

39w0d–40w6d. Babies born between 37 and 39 weeks are “early term”; elective deliveries are recommended to wait until 39 weeks.

Can the due date change?

Yes — providers revise it if first-trimester ultrasound dating differs from the LMP estimate by more than 5–7 days.