bumpcalc.comPregnancy Week Calculator
Estimate your current pregnancy week and day, trimester, and baby size using due date or LMP.
Add your due date or LMP to calculate the exact week and day.
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Frequently Asked Questions
How do I know what week of pregnancy I'm in?
Pregnancy weeks are counted from the first day of your last menstrual period (LMP), not from conception. So at 'Week 1,' you haven't actually conceived yet — conception typically occurs around Week 2-3. Enter your LMP or due date in the calculator above to find your exact week and day.
When does each trimester start and end?
The first trimester covers weeks 1-12, the second trimester weeks 13-27, and the third trimester weeks 28-40 (or until delivery). Each trimester brings different developments and milestones for both the baby and the mother.
Why do doctors count pregnancy from LMP, not conception?
Because most women know when their last period started, but the exact conception date is harder to pinpoint. Ovulation can vary by several days, and sperm can survive up to 5 days in the reproductive tract. Using LMP provides a consistent starting point for all pregnancies.