Week by week

Pregnancy weeks to months

Pregnancy is counted in weeks, but most people talk in months. Slide to your week, or find it in the chart below.

20 weeks

is about 4½ months pregnant, in month 5 of 9

Not sure of your week? Work it out from a date

All nine monthsWeeks 1–40

  1. 1

    Month 1Weeks 1–41st trimester

    1234

    By week 4: a lentil

  2. 2

    Month 2Weeks 5–81st trimester

    5678

    By week 8: a kidney bean

  3. 3

    Month 3Weeks 9–131st trimester

    910111213

    By week 13: a lemon

  4. 4

    Month 4Weeks 14–172nd trimester

    14151617

    By week 17: a pear

  5. 5

    Month 5Weeks 18–222nd trimester

    1819202122

    By week 22: a papaya

  6. 6

    Month 6Weeks 23–272nd trimester

    2324252627

    By week 27: a broccoli

  7. 7

    Month 7Weeks 28–313rd trimester

    28293031

    By week 31: a coconut

  8. 8

    Month 8Weeks 32–353rd trimester

    32333435

    By week 35: a honeydew

  9. 9

    Month 9Weeks 36–403rd trimester

    3637383940

    By week 40: a watermelon

Why weeks don't split neatly into months

Pregnancy is counted as 40 weeks, starting from the first day of your last period, about two weeks before you actually conceive. That's why weeks 1 to 3 come before a test could turn positive.

A calendar month is about 4.3 weeks, so the months above aren't all the same length; some hold four weeks and some five. Different books and apps split them slightly differently, so a week near the edge of a month can be called either one. Your midwife or doctor will always talk in weeks, because weeks are precise.

Common questions

How many weeks is 4 months pregnant?

Month 4 covers weeks 14 to 17. If you're 4 months pregnant, you're somewhere in that range, in your second trimester.

How many weeks is 5 months pregnant?

Month 5 covers weeks 18 to 22. If you're 5 months pregnant, you're somewhere in that range, in your second trimester.

How many weeks is 6 months pregnant?

Month 6 covers weeks 23 to 27. If you're 6 months pregnant, you're somewhere in that range, in your second trimester.

How many weeks is 7 months pregnant?

Month 7 covers weeks 28 to 31. If you're 7 months pregnant, you're somewhere in that range, in your third trimester.

How many weeks is 8 months pregnant?

Month 8 covers weeks 32 to 35. If you're 8 months pregnant, you're somewhere in that range, in your third trimester.

How many weeks is 9 months pregnant?

Month 9 covers weeks 36 to 40. If you're 9 months pregnant, you're somewhere in that range, in your third trimester.

How many months is 20 weeks pregnant?

At 20 weeks you're about 4½ months pregnant, in month 5 of 9. More about week 20.

How many months is 24 weeks pregnant?

At 24 weeks you're about 5½ months pregnant, in month 6 of 9. More about week 24.

How many months is 37 weeks pregnant?

At 37 weeks you're about 8½ months pregnant, in month 9 of 9. More about week 37.

Is pregnancy 9 months or 10 months?

Both are said. Pregnancy is counted as 40 weeks from the first day of your last period. A month is about 4.3 weeks, so 40 weeks is a little over 9 months, or 10 months if you count in four-week blocks. Most people simply say 9 months.

NUGA counts the weeks for you

Enter your due date once and NUGA always knows your week and month, and what's coming up next.

Download on theApp StoreAvailable now

Sources

This page draws on public guidance from:

General information, not medical advice. Last updated October 2026.