Pregnancy Week Calculator
Calculate how many weeks pregnant you are and when each trimester ends.
Understanding Due Date Calculation
Trimesters: 1st (weeks 1-12), 2nd (13-27), 3rd (28-40)
Trimesters
- 1st Trimester: Weeks 1-12 (organ development)
- 2nd Trimester: Weeks 13-27 (movement, growth)
- 3rd Trimester: Weeks 28-40 (final development)
Frequently Asked Questions
How do I count pregnancy weeks?
Counting starts from the first day of your last period, not conception.
What week am I in?
Enter your LMP above and we'll tell you exactly what week you're in.