How Many Weeks Pregnant in Months (Cheat Sheet)

When someone says, “I’m 27 weeks pregnant,” it’s hard to know what that means without doing some quick math. It also doesn’t help that nobody is technically pregnant until the third week or that 40 weeks is still considered the 9th month of pregnancy – c’mon, we all know it’s ten and a million.

Here’s a quick cheat sheet to calculate what week when.

You can click on the links to learn more about each week or sign up for the Pregnancy Calendar to get weekly updates delivered to your inbox.

First trimester

• The first trimester of pregnancy is tricky because pregnancy begins before anyone has ovulated or fertilized an egg. It is easier to calculate the due date from the first day of a period than from conception. Even if you know the exact time of intercourse, you will not know the exact time of conception because it can vary if the sperm is fast or slow.
• 1 week pregnant This is the first day of your last period.
• 2 weeks pregnant lining of uterus preparing for ovulation.
• 3 weeks pregnant Sperm and egg meet. (Conception.)
• 4 weeks pregnant Four weeks is one month pregnant.
• 5 weeks pregnant Five weeks is just over a month pregnant.
• 6 weeks pregnant Six weeks is one and a half months pregnant.
• 7 weeks pregnant Seven weeks is one month and three weeks pregnant. (Almost two months.)
• 8 weeks pregnant Eight weeks is two months pregnant.
• 9 weeks pregnant Nine weeks is just over two months pregnant.
• 10 weeks pregnant Ten weeks is two and a half months pregnant.
• 11 weeks pregnant Eleven weeks is two months and three weeks pregnant. (Almost three months.)
• 12 weeks pregnant Twelve weeks is three months pregnant.
• 13 weeks pregnant Thirteen weeks is more than three months pregnant.

Second Trimester

• The second trimester runs from week 14 to week 27. This is the trimester when morning sickness is likely to subside (or not) and when you start looking cute pregnant as opposed to “are you sure it’s not twins” pregnant.
• 14 weeks pregnant Fourteen weeks is three months and two weeks pregnant.
• 15 weeks pregnant Fifteen weeks is three months and three weeks pregnant. (Almost four months.)
• 16 weeks pregnant Sixteen weeks is four months pregnant.
• 17 weeks pregnant Seventeen weeks is more than four months pregnant.
• 18 weeks pregnant Eighteen weeks is four and a half months pregnant.
• 19 weeks pregnant Nineteen weeks is four months and three weeks pregnant. (Almost five months.)
• 20 weeks pregnant Twenty weeks is five months pregnant.
• 21 weeks pregnant Twenty-one weeks is more than five months pregnant.
• 22 weeks pregnant Twenty-two weeks is five and a half months pregnant.
• 23 weeks pregnant Twenty-three weeks is five months and three weeks. (Almost six months pregnant.)
• 24 weeks pregnant Twenty-four weeks is six months pregnant.
• 25 weeks pregnant Twenty-five weeks is more than six months pregnant.
• 26 weeks pregnant Twenty-six weeks about six and a half months pregnant.
• 27 weeks pregnant Twenty-seven weeks is 6 months and 3 weeks pregnant. (Almost 7 months.)

Third Trimester

• The third trimester runs from week 28 to week 40. It’s the stretch at home even though it rarely feels like it and the last few weeks of pregnancy can feel like a million years.
• 28 weeks pregnant Twenty-eight weeks is 7 months pregnant.
• 29 weeks pregnant Twenty-nine weeks is just over 7 months pregnant.
• 30 weeks pregnant Thirty weeks is 7 and a half months pregnant.
• 31 weeks pregnant Thirty one weeks is 7 months and 3 weeks pregnant. (Almost 8 months pregnant.)
• 32 weeks pregnant Thirty-two weeks is 8 months pregnant
• 33 weeks pregnant Thirty-three weeks is over 8 months pregnant.
• 34 weeks pregnant Thirty-four weeks is 8 and a half months pregnant.
• 35 weeks pregnant Thirty-five weeks is 8 months and three weeks pregnant. (I would probably say “about nine months.)
• 36 weeks pregnant Thirty-six weeks is 9 months pregnant. (But you’re still not done. Sorry.)
• 37 weeks pregnant Thirty-seven weeks is more than 9 months pregnant.
• 38 weeks pregnant Thirty-eight weeks is 9 and a half months pregnant.
• 39 weeks pregnant Thirty-nine weeks is 9 months and three weeks pregnant. (Official full term.)
• 40 weeks pregnant Forty weeks is still considered the 9th month of pregnancy. (Fixed date.)
• 41 weeks pregnant Forty-one weeks is still considered the 9th month of pregnancy. (A week passed.)
• 42 weeks pregnant Forty-two weeks is 9 months and two weeks overdue.

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