Free Tool
Pregnancy Week Calculator
Enter your due date to find out how far along you are, your baby's size, and what trimester you're in.
Enter Your Due Date
How Pregnancy Weeks Are Calculated
Pregnancy is dated from the first day of your last menstrual period (LMP), not from conception. This means you're already considered 2 weeks pregnant at the time of ovulation. A full-term pregnancy is 40 weeks (280 days) from LMP.
Trimesters
- First trimester (weeks 1–12): Critical organ development. Most morning sickness occurs. Heartbeat detectable by week 6.
- Second trimester (weeks 13–27): Baby starts moving. Gender visible on ultrasound (~week 18–20). Energy typically returns.
- Third trimester (weeks 28–40): Rapid weight gain. Lungs mature. Baby positions for delivery. Braxton Hicks contractions begin.
When to See Your Doctor
Schedule your first prenatal appointment between weeks 6–8. Regular check-ups include blood tests, ultrasounds, and glucose screening (weeks 24–28). After week 36, weekly visits are typical.