Pregnancy Week Calculator
Find the current pregnancy week and trimester from either the first day of the last menstrual period (LMP) or the estimated due date.
This estimate is informational. For accurate dating, consult a healthcare provider.
Pick a date
Choose your LMP or estimated due date to see the current pregnancy week.
Frequently asked questions
How is the current week calculated?
We subtract today's date from the first day of the last menstrual period (LMP) and divide by 7. The remainder gives the day into the current week.
When do trimesters change?
Trimester 1 covers weeks 1–12, Trimester 2 covers weeks 13–26, and Trimester 3 covers weeks 27 to delivery.
Can I enter the due date instead?
Yes. Switch the mode to "Estimated due date" and the tool back-calculates the LMP.
Is this medically accurate?
It uses a standard 280-day pregnancy length. Healthcare providers may refine the dates with ultrasound or cycle data.