"How many months is that?" Pick your pregnancy week and day to get the answer the way providers and pregnancy books count it — plus your trimester, your exact day count and how many days are left to go.
The full conversion at a glance. Months of pregnancy aren't neat 4-week blocks — they're 4–5 week buckets so that 40 weeks fits into 9 calendar months. Click any week for a detailed answer for exactly where you are.
| Week | Months pregnant | Trimester | Days pregnant | Days to go |
|---|---|---|---|---|
| 4 weeks | about 1 month | First | 28 | 252 |
| 5 weeks | about 2 months | First | 35 | 245 |
| 6 weeks | about 2 months | First | 42 | 238 |
| 7 weeks | about 2 months | First | 49 | 231 |
| 8 weeks | about 2 months | First | 56 | 224 |
| 9 weeks | about 3 months | First | 63 | 217 |
| 10 weeks | about 3 months | First | 70 | 210 |
| 11 weeks | about 3 months | First | 77 | 203 |
| 12 weeks | about 3 months | First | 84 | 196 |
| 13 weeks | about 3 months | First | 91 | 189 |
| 14 weeks | about 4 months | Second | 98 | 182 |
| 15 weeks | about 4 months | Second | 105 | 175 |
| 16 weeks | about 4 months | Second | 112 | 168 |
| 17 weeks | about 4 months | Second | 119 | 161 |
| 18 weeks | about 5 months | Second | 126 | 154 |
| 19 weeks | about 5 months | Second | 133 | 147 |
| 20 weeks | about 5 months | Second | 140 | 140 |
| 21 weeks | about 5 months | Second | 147 | 133 |
| 22 weeks | about 5 months | Second | 154 | 126 |
| 23 weeks | about 6 months | Second | 161 | 119 |
| 24 weeks | about 6 months | Second | 168 | 112 |
| 25 weeks | about 6 months | Second | 175 | 105 |
| 26 weeks | about 6 months | Second | 182 | 98 |
| 27 weeks | about 6 months | Second | 189 | 91 |
| 28 weeks | about 7 months | Third | 196 | 84 |
| 29 weeks | about 7 months | Third | 203 | 77 |
| 30 weeks | about 7 months | Third | 210 | 70 |
| 31 weeks | about 7 months | Third | 217 | 63 |
| 32 weeks | about 8 months | Third | 224 | 56 |
| 33 weeks | about 8 months | Third | 231 | 49 |
| 34 weeks | about 8 months | Third | 238 | 42 |
| 35 weeks | about 8 months | Third | 245 | 35 |
| 36 weeks | about 9 months | Third | 252 | 28 |
| 37 weeks | about 9 months | Third | 259 | 21 |
| 38 weeks | about 9 months | Third | 266 | 14 |
| 39 weeks | about 9 months | Third | 273 | 7 |
| 40 weeks | about 9 months | Third | 280 | — |
| 41 weeks | 9 months and past your due date | Third | 287 | — |
| 42 weeks | 9 months and past your due date | Third | 294 | — |
The math trips everyone up at least once: pregnancy lasts about 40 weeks, and 40 divided by 4 is 10 — so pregnancy must be 10 months, right? Not quite. A calendar month isn't 4 weeks; it averages about 4.3 weeks (30.4 days). Divide 280 days of pregnancy by the length of a real month and you get just over 9 calendar months, which is why every midwife, book and app describes pregnancy as 9 months long.
To make weeks and months line up in everyday conversation, months of pregnancy are counted as uneven buckets of 4 to 5 weeks. Month 1 covers weeks 1–4, month 3 covers weeks 9–13, month 9 covers weeks 36–40. The boundaries differ slightly between books, but the convention in the chart above is the one most providers and major pregnancy resources use — and the small differences never matter medically, because your care team schedules everything by weeks and days, not months.
One more quirk: because pregnancy is dated from the first day of your last menstrual period, you're counted as "1 month pregnant" only about two weeks after conception. The week number — and therefore the month — describes the calendar of your pregnancy, not the exact age of the baby, which runs about two weeks behind.
Going the other direction — "how many weeks is 6 months pregnant?" — is a range rather than a single number. Our months-to-weeks chart walks through every month and explains why different charts disagree by a week.
A calendar month is about 4.3 weeks long, not 4 — that's why "40 weeks" doesn't equal 10 months. Providers and pregnancy books smooth this out by counting months as uneven buckets of 4 to 5 weeks each, so the 40 weeks of pregnancy fit into 9 calendar months.
Pregnancy lasts about 40 weeks counted from the first day of your last period, which works out to roughly 9 calendar months plus a week — not 10 months. The "10 months" idea comes from wrongly assuming a month is exactly 4 weeks. Since months average about 4.3 weeks, 40 weeks lands at the end of month 9.
At 12 weeks pregnant you are about 3 months pregnant, in the final stretch of your first trimester. The first trimester runs through 13 weeks 6 days, so month 3 covers roughly weeks 9 through 13.
Weeks are simply more precise. Fetal development moves fast — the difference between 24 and 26 weeks matters medically in a way "6 months" can't capture. All screening schedules, term definitions and milestones are defined in weeks and days, so providers stick to that language and convert to months only for everyday conversation.
The days don't change the month. Months of pregnancy are 4–5 week buckets, so every day of week 11 — from 11 weeks 0 days to 11 weeks 6 days — is "about 3 months pregnant". If you want a strict calendar figure instead, divide your total days by 30.44: 11 weeks 4 days is 81 days, which is 2.7 calendar months. Your care team will always write the weeks-and-days version, usually as 11+4 or 11w4d.
Subtract your total days pregnant from 280, the length of a 40-week pregnancy. At 33 weeks 0 days you are 231 days in, so 49 days — 7 weeks — remain. The due date is only an estimate though: about 1 in 20 babies arrives on it exactly, and most are born within two weeks on either side.
The first trimester is weeks 0–13 (months 1–3), the second is weeks 14–27 (months 4–6), and the third is week 28 to birth (months 7–9). The month and trimester boundaries don't line up perfectly because months are uneven 4–5 week buckets, but this is the convention most providers and pregnancy resources use.