Calculate your current pregnancy week, trimester and key milestones from your LMP date.
Enter the first day of the last menstrual period and calculate to see the estimated pregnancy week, trimester and milestone dates.
Pregnancy dating can change after ultrasound assessment or clinical review.
This calculator counts from the first day of the last menstrual period, the conventional starting point for pregnancy dating. A typical estimated due date is about 40 weeks from that date, even though conception usually happens later. The result is therefore a calendar estimate, not a measurement of fetal development.
Irregular cycles, uncertain period dates and later ovulation can shift an LMP-based estimate. A dating ultrasound may give your healthcare team better information and your recorded due date can be revised. Pregnancy, Birth and Baby explains both LMP and ultrasound dating at Working out your due date. Use this tool for planning appointments and milestones, not to decide whether symptoms or pregnancy progress are normal.