Pregnancy Calculator: How Far Along Am I?
Enter your last period, due date, or conception date and see exactly how far along you are — your current week, day, and trimester.
This is what most people know. Prefer your due date or conception date? Switch above.
Free to use. No account required.
How this pregnancy calculator works
Pregnancy is measured from the first day of your last menstrual period (LMP), not from conception, which is why you can be “pregnant” for about two weeks before you conceive. A due date is estimated as 280 days (40 weeks) from that first day. You can start from whichever date you know — enter your last periodif that's what you have (most people do), or switch to your due date or conception date. Either way, the calculator shows exactly how far along you are today: your current week and day, your trimester, your estimated due date, and how many days you have to go.
Pregnancy weeks and trimesters, explained
A full-term pregnancy is about 40 weeks, split into three trimesters:
- First trimesterWeeks 1–13— Early growth and the first big milestones.
- Second trimesterWeeks 14–27— The “honeymoon” stretch, often with more energy and the first kicks.
- Third trimesterWeeks 28–40— Baby gains weight and gets ready to meet you.
How accurate is a due date?
Your due date is an estimate, not a deadline. Only about 1 in 20 babies arrive on their exact due date, and most are born within two weeks before or after it. An early ultrasound gives the most accurate dating, so if your dates and scan differ, your provider's date is the one to trust.
Pregnancy calculator FAQ
How do I know how far along I am in my pregnancy?
Pregnancy is measured from the first day of your last menstrual period, not from conception. Enter your last period date above and this calculator counts forward to show exactly how many weeks and days along you are today, and which trimester you are in. You can also start from your due date or conception date if that is what you know.
Can I calculate how far along I am from my last period?
Yes. The last period option is the default because it is what most people know. Enter the first day of your last menstrual period and the calculator shows your current week and day, your trimester, and your estimated due date. If you know your due date or conception date instead, switch the option above the date box.
Can I work out how far along I am by conception date?
Yes. Choose the conception date option and enter the day you conceived. Because pregnancy is dated from the last period (about two weeks before conception), the calculator adds those two weeks for you, so your week count matches what your doctor and pregnancy apps use.
How is my due date calculated?
A due date is estimated as 280 days (40 weeks) from the first day of your last period. Enter your last period and this calculator counts forward to it; enter a due date and it works backward. Either way you get how far along you are right now.
How many weeks is a full-term pregnancy?
A full-term pregnancy is about 40 weeks, counted from the first day of your last period. Babies born between 37 and 42 weeks are considered full term.
What trimester am I in?
The first trimester is weeks 1 to 13, the second trimester is weeks 14 to 27, and the third trimester is week 28 through birth (around week 40). The calculator shows your current trimester automatically.
How accurate is a due date?
A due date is an estimate, not a deadline. Only about 1 in 20 babies arrive on their exact due date; most are born within two weeks before or after it. An ultrasound in early pregnancy gives the most accurate dating.
What is the difference between "weeks completed" and the week I am in?
When a doctor says you are "20 weeks," you have completed 20 full weeks and are living in week 21, the same way you have completed 1 year on your first birthday but are in your second year. Both numbers are correct; one counts what is done, the other where you are.