Data Saju › Learn saju

The Most Common Birth Month in the US, and What It Is in BaZi

By Data Saju · Published November 2, 2026

In 2021 the most births in the US came in August (330,271) and September, and the fewest per day in January. Turned into BaZi months, which change on solar terms rather than on the 1st, the most common is the 未 Wei (Goat) month (about Jul 7–Aug 7) at 9.2% of births, and the rarest is the 丑 Chou (Ox) month (about Jan 6–Feb 3) at 7.1%.

Which birth month is most common in the US?

August has the most births (9%), but month length matters: per day, September is highest at 10,858 and January lowest at 8,941. The counts are from the National Center for Health Statistics, Births: Final Data for 2021, Table I-2 (tables PDF), which totals 3,664,292 births, and the twelve months here add up to that. One caution: January 2021 was about 9% below January 2020 (press coverage of NCHS data put January 2020 near 304,000), likely a pandemic effect, so the winter dip is a little deeper than usual that year. I could check the monthly figures against only this one official table.

What are those months in BaZi?

BaZi months do not start on the 1st. They turn on twelve solar terms, around the 4th to 8th of each month, so each BaZi month straddles two calendar months (see the twelve earthly branches). To convert, I assumed births are spread evenly within each calendar month, built the BaZi month pillar for every one of the 365 days of 2021 with this site's engine, and added each day's share of that month's births. Noon was used for every day, so a day with a solar term has a small error.

The 未 Wei (Goat) month (9.2%) and the 申 Shen (Monkey) month (9.1%) lead, with the 酉 You (Rooster) month close behind at 8.8%. The 丑 Chou (Ox) month is the lowest at 7.1%, against 7.9% if every day had equal births.

How does South Korea compare?

Korea is almost the mirror image. Statistics Korea's monthly births for 2019–2021 (2021 provisional release, Table 9) peak in January (9.8%) and bottom out in December (6.9%). In BaZi months, the 丑 Chou (Ox) month is the most common there at 9.3%, and the 子 Zi (Rat) month the rarest at 7.1%. The same Ox month is the rarest in the US (7.1%) and the most common in Korea. (The 2021 figures there are provisional, and I could not open the agency's own database, so I used the release.)

Earth takes about a third in both countries because four of the twelve month branches (Chou, Chen, Wei and Xu) are Earth. That is a property of the calendar, not of people.

What share of babies are in the "previous" BaZi year?

The BaZi year turns at Lichun (about February 4), not on January 1, so a baby born in January has last year's year pillar and zodiac animal. With equal births every day that would be 9.3% of the year. In the US, where January and February are low, it is about 8.3%. In Korea, where January is the busiest month, it is about 10.9%. See our Dragon-year article for how that plays out around Lunar New Year.

Does a common birth month mean a luckier chart?

No. A BaZi chart is read from all eight characters and the day master, not from how many babies share the month. The data show when people are born, and they cannot tell you why. If you'd like to see your own month pillar and elements, the free reading will calculate them.

Frequently asked questions

What is the most common birth month in the US? August has the most births in total (9% of 2021), and per day the peak is September (10,858 a day). January is the lowest per day (8,941).

What is the most common BaZi month? In the US data, the 未 Wei (Goat) month, about July 7 to August 7, at 9.2% of births. In Korea it is the 丑 Chou (Ox) month at 9.3%.

When does a BaZi month start? On a solar term, not the 1st. The twelve starts are Lichun (Feb 4), Awakening of Insects (Mar 6), Clear and Bright (Apr 5), Start of Summer (May 6), Grain in Ear (Jun 6), Minor Heat (Jul 7), Start of Autumn (Aug 8), White Dew (Sep 8), Cold Dew (Oct 8), Start of Winter (Nov 7), Major Snow (Dec 7) and Minor Cold (Jan 6), give or take a day.

Is a January baby in the previous BaZi year? Yes, if born before Lichun in early February. That is about 8.3% of US births and 10.9% of Korean births.

Is a more common birth month luckier? No. Nothing in BaZi reads a chart by how common its month is.

US counts are from NCHS Births: Final Data for 2021 (Table I-2), Korea's from Statistics Korea's 2021 provisional birth release. Shares are this site's calculation, assuming births are even within each calendar month; the real daily pattern differs a little.

Read next