Pregnancy Due Date Calculator
Enter the first day of your last menstrual period (LMP).
Estimated due date
April 4, 2027
- Current week
- 0w 0d
- Trimester
- 1
How it works
We use Naegele's rule: add 280 days to your LMP for the estimated due date.
Formula
Due date = LMP + 280 days
Worked example
LMP Jan 1 → due ≈ Oct 8.
FAQ
- How accurate?
- A good estimate for most pregnancies — ultrasound dating is more precise.
- Cycle length adjustment?
- Current version assumes a standard 28-day cycle.
- When to see a doctor?
- As soon as you suspect pregnancy. This calculator is informational only.