Pregnancy Calculator
Current week of pregnancy, trimester, and days until your due date, from your last period.
days
Worth Knowing
This tracks where you are in pregnancy — current week, trimester, and days remaining — counting from the first day of your last period, which is the convention obstetricians use. That dating quirk means you're considered about two weeks 'pregnant' before conception actually occurred, so gestational age always runs ahead of the true age since fertilization. Trimester boundaries (weeks 1–12, 13–27, 28–birth) are approximate markers, and an ultrasound remains the most accurate way to confirm dates.
How to Use
- Enter Last menstrual period into the first field of the Pregnancy Calculator.
- Fill in the rest: Cycle length.
- Your result appears instantly as you type — there's no submit button or page reload.