Pregnancy Week Calculator
Find out how many weeks pregnant you are, your trimester, and days left to your due date.
LMP + 280 days = estimated due date (Naegele's rule)
Enter your last period date to see how far along you are.
This is an estimate based on your last period and not medical advice. Consult your doctor or midwife to confirm gestational age.
Frequently Asked Questions
How many weeks pregnant am I?
Pregnancy is dated from the first day of your last menstrual period (LMP), not from conception. The calculator counts the days from your LMP to today and shows them as completed weeks plus days — for example, "12 weeks 3 days".
Why is gestational age counted from my last period?
Because the exact day of conception is rarely known, clinicians date pregnancy from the LMP by convention. This means you are counted as about 2 weeks "pregnant" before conception actually occurs — it keeps dating consistent across pregnancies.
How are the trimesters defined?
The first trimester is weeks 0–13, the second is weeks 14–27, and the third is week 28 onward until birth. The calculator labels your current trimester automatically.