Your doctor talks in weeks. Your mum, your coworkers, and everyone in the lift asks how many months along you are. The two never quite match, and that mismatch is why this question gets searched so often.
Why weeks and months don't match up
A pregnancy runs about 40 weeks from your last period. If a month were a neat four weeks, that would be 10 months. But calendar months actually average around 4.3 weeks, so 40 weeks lands at roughly nine months. That extra third of a week per month is the whole reason it feels off. Check your exact week first with the pregnancy week calculator.
Weeks to months chart
- 1 month: weeks 1–4
- 2 months: weeks 5–8
- 3 months: weeks 9–13 (end of first trimester)
- 4 months: weeks 14–17
- 5 months: weeks 18–22
- 6 months: weeks 23–27 (end of second trimester)
- 7 months: weeks 28–31
- 8 months: weeks 32–35
- 9 months: weeks 36–40
Treat these groupings as approximate. There is no single official way to carve weeks into months, so you will run into charts that disagree by a week here or there.
Why your provider sticks with weeks
Weeks are simply more precise. Screening tests, the anatomy scan, and "term" itself are all pinned to exact weeks (term, for instance, is 37 weeks). Months are too blunt an instrument for that kind of timing, which is why your notes always read "24 weeks" and never "6 months." The pregnancy week guide follows what is happening week by week.
From weeks to your due date
Once you know your week, your due date is just the day you hit 40 weeks. The due date calculator will show it.