How many months pregnant are you?
Your midwife or doctor counts pregnancy in weeks, but family and friends ask how many months you are. This pregnancy month calculator converts weeks pregnant into the month of pregnancy and shows why answers differ: the common 9-month chart, real calendar months, and 10 lunar months of four weeks each. Month names are shown in Hindi too — पहला महीना to नौवाँ महीना — for the way months are often spoken about in India.
Enter the weeks and days from your scan report or app, or the first day of your last period, or your due date. It is information only, not medical advice, and runs in your browser.
How to use the Pregnancy Month Calculator (Weeks to Months)
- Choose what you know: weeks pregnant, your last period or your due date.
- Type the weeks and days (for example 20 weeks 3 days), or pick the date.
- Read your month on the 9-month chart, the calendar months completed and the lunar month.
- Scroll the table to see every month with its weeks and dates. Copy result copies the summary.
Pregnancy Month Calculator (Weeks to Months) features
Three conventions side by side
The 9-month chart, calendar months (weeks ÷ 4.35) and 10 lunar months, so you can see why people give different answers.
Hindi month names
पहला, दूसरा, तीसरा … नौवाँ महीना, and the “running month” the way it is often said in India.
Dates for every month
Each month’s start and end date, worked from your weeks, last period or due date.
Why a pregnancy is “9 months” but 40 weeks
Pregnancy is dated from the first day of the last period, so a full-term pregnancy is 40 weeks, or 280 days. An average calendar month is 365.25 ÷ 12 = 30.44 days, or about 4.35 weeks. 280 days is therefore about 9.2 calendar months — nine months and roughly a week. Divide the weeks by 4.35 to get calendar months: 20 weeks is about 4.6 months completed.
A lunar month of 28 days (exactly 4 weeks) divides 280 days evenly into 10 lunar months, which is why some books and countries speak of ten months of pregnancy.
The 9-month chart
Most pregnancy apps and charts fit the 40 weeks into nine months of four or five weeks: weeks 1–4, 5–8, 9–13, 14–17, 18–22, 23–27, 28–31, 32–35 and 36–40. “Week 21” means the 21st week, which begins at 20 weeks 0 days, so 20 weeks 0 days is month 5. Other charts move a boundary by a week, so a friend’s app may say month 4 when this one says month 5.
Months in India: the “running” month
In everyday Indian usage people often say which month is running: once three months are complete, “चौथा महीना चल रहा है” — the fourth month is running. The calculator shows this from completed calendar months, and the month on the 9-month chart. The two usually agree but can differ by one around the boundaries: at 13 weeks the chart says month 4 while only about three calendar months have passed. Your doctor’s reports, scans and tests will still use weeks.
| Lunar month | Weeks pregnant | Hindi |
|---|---|---|
| 1 | 0w 0d – 3w 6d | पहला |
| 2 | 4w 0d – 7w 6d | दूसरा |
| 3 | 8w 0d – 11w 6d | तीसरा |
| 4 | 12w 0d – 15w 6d | चौथा |
| 5 | 16w 0d – 19w 6d | पाँचवाँ |
| 6 | 20w 0d – 23w 6d | छठा |
| 7 | 24w 0d – 27w 6d | सातवाँ |
| 8 | 28w 0d – 31w 6d | आठवाँ |
| 9 | 32w 0d – 35w 6d | नौवाँ |
| 10 | 36w 0d – 39w 6d | दसवाँ |
Trimesters and related tools
Trimesters are another way to split the same 40 weeks. ACOG puts the second trimester at 14 weeks 0 days and the third at 28 weeks; the NHS starts the second at 13 weeks. See exact dates with the trimester calculator, or a full week-by-week calendar and scan dates with the pregnancy due date calculator.
Pregnancy Month Calculator (Weeks to Months) FAQ
How many months is 20 weeks pregnant?
Month 5 on the usual 9-month chart (weeks 18–22), about 4.6 calendar months completed, and lunar month 6 of 10.
How do I convert pregnancy weeks to months?
Divide the weeks by 4.35 for calendar months completed, or look the week up on the 9-month chart. Remember that “week 21” is the week that starts at 20 weeks.
Is pregnancy 9 months or 10 months?
Both, depending on the month. 40 weeks is about 9.2 calendar months, or exactly 10 lunar months of 4 weeks.
How many weeks is 6 months pregnant?
On the 9-month chart, month 6 is weeks 23–27, from 22 weeks 0 days to 26 weeks 6 days. By calendar months, 6 months completed is about 26 weeks.
What is the pregnancy month in Hindi?
Months are counted as पहला, दूसरा, तीसरा, चौथा, पाँचवाँ, छठा, सातवाँ, आठवाँ and नौवाँ महीना. The calculator shows the Hindi name next to each month.
Why does my app show a different month?
Apps use different charts and some count completed months while others count the running month. Compare weeks and days, which every source agrees on.