Weeks pregnant in months.

A pregnancy of 40 weeks is about 9 months and 1 week, because a month averages 4.345 weeks. To convert, divide the weeks by 4.345: 24 weeks is 5.5 months, so month 6 of pregnancy. Counting 4 weeks per month falls short, since 9 × 4 is only 36 weeks. The chart below converts all 40 weeks.

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Convert weeks to months

Enter the gestational age your provider gave you.

Week
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Pregnancy monthcalterix
Month 6
24 weeks and 3 days = 5 months and 3 weeks, 2nd trimester
5.6 monthsof 9.2
An approximate conversion. Prenatal care is tracked in weeks.

Chart: weeks pregnant in months

The chart turns each of the 40 weeks into a pregnancy month, completed months, and trimester.

WeekPregnancy monthCompleted monthsTrimester
1Month 101st trimester
2Month 101st trimester
3Month 101st trimester
4Month 101st trimester
5Month 211st trimester
6Month 211st trimester
7Month 211st trimester
8Month 211st trimester
9Month 321st trimester
10Month 321st trimester
11Month 321st trimester
12Month 321st trimester
13Month 321st trimester
14Month 432nd trimester
15Month 432nd trimester
16Month 432nd trimester
17Month 432nd trimester
18Month 542nd trimester
19Month 542nd trimester
20Month 542nd trimester
21Month 542nd trimester
22Month 652nd trimester
23Month 652nd trimester
24Month 652nd trimester
25Month 652nd trimester
26Month 652nd trimester
27Month 762nd trimester
28Month 763rd trimester
29Month 763rd trimester
30Month 763rd trimester
31Month 873rd trimester
32Month 873rd trimester
33Month 873rd trimester
34Month 873rd trimester
35Month 983rd trimester
36Month 983rd trimester
37Month 983rd trimester
38Month 983rd trimester
39Month 983rd trimester
40Month 993rd trimester
Conversion at 4.345 weeks per month.

How to convert weeks to months

Months = weeks ÷ 4.345
Current month = whole number of Months + 1
Example: 24 weeks ÷ 4.345 = 5.52. That is 5 completed months and the 6th month underway.

Many people use 4 weeks per month, which leaves out about 4 weeks of pregnancy: 9 × 4 = 36, and a full pregnancy is 40. A calendar month runs 4 to 4.5 weeks, so the right math uses the 4.345 average.

Doctors speak in weeks because weeks are more precise. Months are a rough way to talk about pregnancy with friends and family.

Not sure how far along you are? Use the due date calculator with your last period or ultrasound results.

Back to the calculator

Main calculatorDue date calculatorWeeks pregnant, trimester, and your due date

Frequently asked questions

How many months is a 40 week pregnancy?

About 9 months and 1 week. A full pregnancy is 40 weeks, and a month averages 4.345 weeks.

How many months is 20 weeks pregnant?

20 weeks is 4 months and 3 weeks, so you are in month 5 and about halfway through the pregnancy.

How many months pregnant am I at 12 weeks?

At 12 weeks you are almost 3 months along, in month 3, at the end of the 1st trimester.

When is a baby considered full term in months?

Full term starts at 39 weeks, about 9 months. Early term begins at 37 weeks, a little over 8 months.

Sources and review

Standard public-domain formulas. Every calculation is checked against independent numeric tests before it goes live.

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