The Pregnancy Week Calculator tells you exactly how far along you are. Enter the first day of your last menstrual period and your cycle length, and it shows how many weeks and days pregnant you are today, your current trimester, a progress bar toward 40 weeks, and your estimated due date.
Pregnancy is measured in weeks from the first day of your last period, which is the standard doctors use. The calculation runs entirely in your browser, so none of your dates are uploaded or stored.
How to check how many weeks pregnant you are
- Select the first day of your last menstrual period (LMP).
- Adjust the cycle-length slider if your cycle isn’t 28 days.
- Read your current week and day, trimester, and progress toward 40 weeks.
- See your estimated due date and how many days are left.
How pregnancy weeks are counted
Pregnancy is counted from the first day of your last period, not from conception. Because ovulation and conception happen about two weeks into your cycle, you are considered around two weeks pregnant at the moment of conception. A full-term pregnancy is about 40 weeks measured this way.
The three trimesters are roughly weeks 1–13 (first), 14–27 (second), and 28–40 (third). The progress bar shows how far you are through the 40 weeks.
Good to know
- A normal, full-term birth can happen any time from 37 to 42 weeks.
- An early ultrasound gives the most accurate dating and may adjust your week count.
- Your due date is only an estimate — very few babies arrive on it exactly.
- This tool is for general information and is not a substitute for medical advice.
Frequently Asked Questions
How many weeks pregnant am I?
This calculator counts the weeks and days from the first day of your last period to today, which is how gestational age is measured. Enter your LMP to see your current week.
Why am I “two weeks pregnant” at conception?
Because pregnancy is dated from your last period, which is about two weeks before ovulation and conception. So at the time of conception you are already counted as roughly two weeks pregnant.
Which trimester am I in?
The first trimester is weeks 1–13, the second is 14–27, and the third is 28 onward. The calculator shows your current trimester based on your week.
Is the week count exact?
It is an estimate based on your last period. An ultrasound, especially in the first trimester, dates the pregnancy more precisely and may revise the count.