Instantly calculate how far along you are in your pregnancy and which trimester you're in.
Enter the first day of your last menstrual period. The calculator shows your current pregnancy week, trimester, and estimated due date.
Pregnancy is divided into three trimesters: first (weeks 1–12), second (weeks 13–27), and third (weeks 28–40+). Each trimester brings distinct developmental milestones.
The LMP method is accurate within ±2 weeks. Only 5% of babies are born exactly on their due date. First trimester ultrasound is more accurate.
Pregnancy is counted from the first day of your last menstrual period (LMP), not from conception. Week 1 starts on your LMP date even though fertilization hasn't occurred yet.