How many months is 20 weeks pregnant?

20 weeks is 5 months pregnant, in the second trimester. You are about halfway through pregnancy.

Is 9 months the full pregnancy?

Yes. A full-term pregnancy is counted as 40 weeks (9 months) from the first day of your last menstrual period. Babies born between 37 and 42 weeks are considered full-term.

Why don't weeks divide evenly into months?

Calendar months have 28-31 days, but pregnancy months are rounded to 4-5 weeks. That is why 40 weeks of pregnancy equals 9 months rather than 10.

When does each trimester start and end?

First trimester: weeks 1-13. Second trimester: weeks 14-26. Third trimester: weeks 27-40.

Weeks to months pregnancy calculator

Enter your current pregnancy week (or month) and see the conversion, trimester, and where you are in pregnancy.

Your pregnancy week (1-40)

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Full pregnancy breakdown

Month	Weeks	Trimester
1	1–4	T1
2	5–8	T1
3	9–13	T1
4	14–17	T2
5	18–21	T2
6	22–26	T2
7	27–30	T3
8	31–35	T3
9	36–40	T3

Common questions

20 weeks is 5 months pregnant, in the second trimester. You are about halfway through pregnancy.
Yes. A full-term pregnancy is counted as 40 weeks (9 months) from the first day of your last menstrual period. Babies born between 37 and 42 weeks are considered full-term.
Calendar months have 28-31 days, but pregnancy months are rounded to 4-5 weeks. That is why 40 weeks of pregnancy equals 9 months rather than 10.
First trimester: weeks 1-13. Second trimester: weeks 14-26. Third trimester: weeks 27-40.