About the Pregnancy Due Date Calculator
This estimates a due date using Naegele's rule (last period plus about 280 days), adjusted for your cycle length, and shows your current gestational age and trimester. It's informational — your provider's dating takes precedence.
How it’s calculated
Due date = first day of last period + 280 days, shifted by any difference from a 28-day cycle.
Example calculation
A last period starting January 1 with a 28-day cycle gives an estimated due date around October 8.
Frequently asked questions
How accurate is a due date?
It's an estimate — only about 1 in 20 babies arrives on the exact date, and full term spans weeks around it. An early ultrasound gives more accurate dating.
Should I rely on this over my doctor?
No. This is informational only; your healthcare provider's dating and guidance should always take precedence.
This tool provides a general, informational estimate only. It is not medical advice and cannot diagnose, treat, or replace guidance from a qualified healthcare professional. Individual health depends on many factors this estimate does not capture. If you have questions about your health, talk to a doctor.