Pregnancy Due Date Calculator
Estimate your pregnancy due date from your last period, plus how far along you are.
Based on Naegele's rule: due date ≈ last period + 280 days (40 weeks).
DISCLAIMER: This is an estimate only. Only about 1 in 20 babies are born on their exact due date, and cycle length varies. Always confirm with your healthcare provider.
What Is the Pregnancy Due Date Calculator?
The Pregnancy Due Date Calculator estimates your baby's due date from the first day of your last menstrual period (LMP) using Naegele's rule (LMP + 280 days). It also estimates conception date, how many weeks along you are, and your current trimester. Everything is calculated locally.
How It Works
Enter the first day of your last period. The estimated due date, conception date, weeks pregnant and trimester update instantly.
When to Use It
Use it for a quick estimate early in pregnancy or to track your progress week by week.
Frequently Asked Questions
- How accurate is it?
- It's an estimate. Cycle length varies and only about 1 in 20 babies arrive on the exact due date. An ultrasound dating scan from your provider is more precise.
Last reviewed: 2026-06-27