20 weeks in months: how far along you are
20 weeks pregnant is month 5 of pregnancy, in the second trimester. In calendar terms, 20 weeks is about 4.6 calendar months (4 months and 3 weeks). You’re 50% of the way to a 40-week due date, with 20 weeks to go.
A calendar calculation, not medical advice. Your provider’s dating ultrasound is the reference for your due date. Nothing you type leaves this page.
20 weeks at a glance
| Measure | At 20 weeks |
|---|---|
| Pregnancy month | Month 5 (weeks 18–22) |
| Trimester | Second |
| Calendar months | 4.6 (4 months and 3 weeks) |
| Counting 4-week months | 5.0 |
| Days pregnant | 140 |
| Weeks left until 40 | 20 |
Why some charts say 20 weeks is 5 months and others say 4
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 20 in month 5. A calendar month is about 4.35 weeks (30.44 days), so 20 weeks of calendar time is 4.6 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 20
- You’re in the second trimester, which runs from week 14 through 27 weeks and 6 days. (source)
- In a healthy pregnancy, prenatal visits are usually about every four weeks until week 28. (source)
- The detailed mid-pregnancy (anatomy) ultrasound is usually done between 18 and 22 weeks. (source)
Every pregnancy is different, and your provider’s schedule comes first.
Weeks around week 20
| Week | Pregnancy month | Calendar months | Trimester |
|---|---|---|---|
| 18 weeks | Month 5 | 4.1 | Second |
| 19 weeks | Month 5 | 4.4 | Second |
| 20 weeks | Month 5 | 4.6 | Second |
| 21 weeks | Month 5 | 4.8 | Second |
| 22 weeks | Month 5 | 5.1 | Second |
See every week from 1 to 42 on the pregnancy weeks to months chart.
Questions
Is 20 weeks pregnant 5 months?
On a standard pregnancy chart, yes: week 20 falls in month 5. In calendar time it’s 4.6 months, so counting only finished calendar months gives 4.
How many months is 20 weeks?
Divide the days by the average calendar month: 20 × 7 = 140 days, and 140 ÷ 30.44 = 4.6 months (4 months and 3 weeks). On a pregnancy chart, week 20 is month 5.
How many days is 20 weeks pregnant?
140 days, counted from the first day of your last menstrual period.
What trimester is 20 weeks?
The second trimester.
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”
- UT Southwestern Medical Center, on the 18- to 22-week ultrasound
This page explains calendar math. It isn’t medical advice; ask your provider about your own pregnancy.