Pregnancy Week Calculator
Find out exactly how many weeks and days pregnant you are, your trimester and month, your baby’s size this week and how many days are left — free and instant.
How many weeks pregnant am I?
Pregnancy is counted in weeks from the first day of your last period, so in the first two weeks you are not actually pregnant yet — ovulation and conception happen around week 2. A full-term pregnancy is about 40 weeks. If you know your due date from a scan, enter it instead — it is usually more accurate than period dates.
Pregnancy weeks, months and trimesters
| Month | Weeks | Trimester |
|---|---|---|
| 1 | 1–4 | 1st (weeks 1–12) |
| 2 | 5–8 | |
| 3 | 9–13 | |
| 4 | 14–17 | 2nd (weeks 13–27) |
| 5 | 18–22 | |
| 6 | 23–27 | |
| 7 | 28–31 | 3rd (weeks 28–40) |
| 8 | 32–35 | |
| 9 | 36–40 |
Months do not divide evenly into weeks, so different books split them slightly differently. Doctors always use weeks.
Eating for your stage matters — get a free pregnancy diet plan for your trimester.
Frequently asked questions
How do I calculate how many weeks pregnant I am?
Count the days from the first day of your last period to today and divide by 7. For example, 94 days is 13 weeks and 3 days, which means you are in week 14.
Is 3 months pregnant 12 or 13 weeks?
The end of the third month is usually counted as about 13 weeks. That is also roughly when the first trimester ends.
When does the second trimester start?
Around week 13. The third trimester starts at week 28.
Sources: NHS: Pregnancy week by week · ACOG: Methods for estimating the due date
Reviewed for accuracy against the sources above. This page is general information, not medical advice — talk to your doctor or a registered dietitian about your own needs.