Pregnancy Calculator
See how far along you are, your trimester, and your due date.
Runs in your browser — nothing is sent or saved.
How to see how far along you are
- Choose what to work from: your last period, your due date, or a conception date.
- Enter that date.
- For the last-period method, set your average cycle length.
- Read how many weeks pregnant you are, your trimester, and the due date.
How far along am I
This pregnancy calculator answers how far along am I by counting from the first day of your last menstrual period to today, which gives your gestational age in weeks and days. Doctors and midwives measure pregnancy this way, from the last period rather than from conception, so being "8 weeks pregnant" usually means eight weeks since that date, roughly six weeks since conception. The tool also works backward from a due date or a conception date if that is what you know, and it tracks your pregnancy week by week.
Gestational age and weeks pregnant
Gestational age is the standard measure of how many weeks pregnant you are. A full-term pregnancy is about 40 weeks from the last period. Because it is counted from the last period, gestational age is normally a couple of weeks more than the time since conception. The tool shows your age in weeks and days, the percentage of the 40 weeks completed, and the days left.
The three trimesters
Pregnancy is split into three trimesters. The tool lists the date range for each based on your dates.
| Trimester | Weeks | About |
|---|---|---|
| First | 0 to 13 | conception through early development |
| Second | 14 to 27 | often the most comfortable stretch |
| Third | 28 to 40 | growth and preparing for birth |
Trimester boundaries follow the American College of Obstetricians and Gynecologists (ACOG): the first runs through 13 weeks 6 days, the second from 14 weeks, the third from 28 weeks.
An estimate, not medical advice
How far along you are is an estimate that depends on your cycle and can be revised by an ultrasound. It is not a diagnosis or medical advice, and it cannot speak to your individual pregnancy. Your doctor or midwife confirms your dates and follows your care. Always rely on their guidance.
FAQ
How many weeks pregnant am I?
Count from the first day of your last period to today. Enter that date and this tool shows your gestational age in weeks and days, which is how weeks pregnant is normally measured.
Is pregnancy measured from conception or my last period?
From the first day of your last period. That is why gestational age is usually about two weeks more than the time since conception.
What trimester am I in?
The first trimester runs through week 13, the second from weeks 14 to 27, and the third from week 28 to birth. The tool highlights the one your dates fall in.
Can this replace an ultrasound?
No. A scan measures the baby directly and is more accurate, and your care team uses it to confirm or revise your dates. This tool is only an estimate.
Is my information private?
Yes. Everything is calculated in your browser and nothing you enter is uploaded or saved.