How Many Weeks for 6 Months Pregnant?

Six months pregnant is generally considered to span weeks 23 through 27, placing you in the latter half of the second trimester.

You’ve probably noticed that pregnancy weeks and months don’t line up the way you’d expect. A month isn’t exactly four weeks, and pregnancy is counted from the first day of your last menstrual period — a 40‑week timeline that adds up to roughly nine months plus an extra week. That mismatch is why “six months pregnant” doesn’t have a single, universal week number.

This article will explain the most widely accepted week range for the sixth month, why the confusion exists, and what’s happening with your baby during this stage. You’ll also get practical ways to track your own pregnancy without the guesswork.

What Weeks Make Up the Sixth Month

The sixth month of pregnancy is most commonly defined as weeks 23 through 27. This places you at the end of the second trimester, just before the third trimester begins at week 28. Planned Parenthood, along with many other medical organizations, uses this range for the sixth month.

Some sources may define the sixth month slightly differently — for example, weeks 21‑24 or 22‑26 — depending on whether they count from the first day of the last menstrual period or from conception. The variation isn’t cause for concern; it’s simply a result of different starting points. For most clinical and tracking purposes, weeks 23‑27 is the accepted answer.

Why the Week‑Month Confusion Happens

The root of the confusion is that pregnancy is measured in weeks, not months, and months aren’t uniform lengths. Here are the key reasons the numbers feel mismatched:

• 40 weeks = 280 days: That’s about 9 calendar months and one week, but because months vary from 28 to 31 days, dividing 40 by 4 gives 10 months — which isn’t accurate either.
• Trimesters divide weeks, not months: First trimester is weeks 1‑13, second is weeks 14‑27, third is weeks 28‑40. The sixth month spans the tail end of the second trimester.
• Due date confusion: Many people assume the due date falls exactly 9 months after conception. In reality, it’s 40 weeks from the last menstrual period, which is a little over 9 months.
• Different counting methods: Some pregnancy apps calculate from ovulation, which can shift the week numbers slightly.
• Medical vs. everyday language: Obstetricians and midwives talk in weeks and trimesters; friends and family talk in months. That mismatch creates the question.

So when someone asks “How many weeks for 6 months pregnant?” the most common clinical answer is weeks 23‑27, but it’s fine to use that as a guide rather than a fixed rule.

Fetal Development at 24 Weeks (Mid‑Sixth Month)

At 24 weeks, the average fetus is about 6 inches long and weighs roughly 9 ounces. Womenshealth.gov provides a detailed reference on fetal size at 24 weeks along with other milestones. By this point, the fetus can hear sounds, swallow amniotic fluid, and has started to develop eyebrows, eyelashes, and taste buds.

During weeks 23 through 27, growth accelerates quickly. Here’s a look at the major developments week by week:

*The 27‑week size estimate comes from one pregnancy resource; individual measurements vary widely. These milestones are typical, but every pregnancy progresses a little differently.

How to Track Your Progress Accurately

Instead of trying to convert weeks to months in your head, here are practical steps to know exactly where you are in your pregnancy:

1. Know your LMP: Your provider calculates gestational age from the first day of your last menstrual period. That’s the standard method used for all official due dates.
2. Use a pregnancy app: Most apps automatically show your current week, the month equivalent, and upcoming milestones. They follow the 40‑week framework.
3. Ask at appointments: Your obstetrician or midwife will confirm your current week and trimester. They can also tell you what to expect in the coming weeks.
4. Focus on trimesters for big‑picture planning: The second trimester (weeks 14‑27) contains the entire sixth month, so if you’re in that window, you know you’re in the “golden period” when early nausea often subsides and energy picks up.

Remember that due dates are estimates. Only about 4% of babies arrive exactly on their assigned due date, so use the week/month conversion as a general guide, not a strict schedule.

When Does the Sixth Month End?

The sixth month ends at week 27. At week 28, the third trimester officially begins. Per the Cleveland Clinic’s comprehensive overview of pregnancy lasts 40 weeks, the transition between trimesters is at 28 weeks, making the sixth month the final month of the second trimester.

At 27 weeks, the fetus is about 14.5 inches long and weighs roughly 2 pounds. From this point, the third trimester runs from week 28 to week 40 (or a little longer for some). Here’s a quick reference for how the trimesters break down:

Some sources may place the sixth month at weeks 21‑24, but the most common clinical framework uses weeks 23‑27. If you’re ever unsure, your obstetrician or midwife can clarify exactly where you stand.

The Bottom Line

Six months pregnant is generally considered weeks 23 through 27 — the tail end of the second trimester. During this time, the fetus grows rapidly, develops senses like hearing and taste, and prepares for the final stretch of pregnancy. Tracking by weeks and trimesters gives you a clearer picture than trying to match months exactly.

Your obstetrician or midwife can confirm your exact gestational age based on your last menstrual period or early ultrasound, so if your pregnancy app’s month conversion feels off, they’re your best resource for an accurate timeline.