40 weeks in months: how far along you are
40 weeks pregnant is month 9 of pregnancy, in the third trimester. In calendar terms, 40 weeks is about 9.2 calendar months (9 months and 1 week). Week 40 is the estimated due date, 280 days from the first day of your last period.
A calendar calculation, not medical advice. Your provider’s dating ultrasound is the reference for your due date. Nothing you type leaves this page.
40 weeks at a glance
| Measure | At 40 weeks |
|---|---|
| Pregnancy month | Month 9 (weeks 36–40) |
| Trimester | Third |
| Calendar months | 9.2 (9 months and 1 week) |
| Counting 4-week months | 10.0 |
| Days pregnant | 280 |
| Weeks left until 40 | 0 |
Pregnancy months vs. calendar months at 40 weeks
Pregnancy months are counted in two ways. Most US pregnancy charts group the 40 weeks into nine “pregnancy months” of four or five weeks each, which puts week 40 in month 9. A calendar month is about 4.35 weeks (30.44 days), so 40 weeks of calendar time is 9.2 months. Both answers are correct for what they measure; your provider will track the pregnancy in weeks.
What’s usually on the calendar around week 40
- You’re in the third trimester, which starts at week 28. (source)
- From week 36 until delivery, visits are usually weekly. (source)
- Early term runs from 37 weeks through 38 weeks and 6 days. Full term runs from 39 weeks through 40 weeks and 6 days. (source)
Every pregnancy is different, and your provider’s schedule comes first.
Weeks around week 40
| Week | Pregnancy month | Calendar months | Trimester |
|---|---|---|---|
| 38 weeks | Month 9 | 8.7 | Third |
| 39 weeks | Month 9 | 9.0 | Third |
| 40 weeks | Month 9 | 9.2 | Third |
| 41 weeks | Past 40 weeks | 9.4 | Third |
| 42 weeks | Past 40 weeks | 9.7 | Third |
See every week from 1 to 42 on the pregnancy weeks to months chart.
Questions
How many months is 40 weeks?
About 9.2 calendar months, or month 9 on a standard pregnancy chart.
Is 40 weeks pregnant 9 months?
Yes, on both counts: week 40 falls in month 9 of a standard pregnancy chart, and it is 9.2 months in calendar time.
How do you convert 40 weeks to months?
Divide the days by the average calendar month: 40 × 7 = 280 days, and 280 ÷ 30.44 = 9.2 months (9 months and 1 week). On a pregnancy chart, week 40 is month 9.
How many days is 40 weeks pregnant?
280 days, counted from the first day of your last menstrual period.
What trimester is 40 weeks?
The third trimester.
40 weeks is how many months on a calendar?
40 weeks in months is about 9.2 calendar months. Counted in 4-week blocks instead, it’s 10.0.
Track every week on paper
The printable pregnancy planner has this chart, trimester calendars, an appointment log and a 40-week countdown.
Sources
- ACOG, “How Your Fetus Grows During Pregnancy”
- Cleveland Clinic, “Your Prenatal Appointment Schedule”
- NICHD, “Know Your Terms”
This page explains calendar math. It isn’t medical advice; ask your provider about your own pregnancy.