The Number 12: Months, Zodiac, Hours and the Dozen, Why Is It Everywhere?

Key takeaways

• 12 divides by 1, 2, 3, 4 and 6: that's what makes it so handy for measuring, counting and sharing.

• It partly comes from the sky: a year contains about 12 lunar cycles, hence 12 months and 12 zodiac signs.

• In numerology, 12 reduces to 3 (1 + 2), the number of expression.

A Highly Divisible Number

12 has six divisors: 1, 2, 3, 4, 6 and 12. 10, the base of our number system, has only four (1, 2, 5, 10). Twelve items split evenly into halves, thirds, quarters or sixths, which explains the success of the dozen in trade and of units based on 12: 12 inches in a foot, and, in Britain until 1971, 12 pence in a shilling.

A practical explanation is sometimes suggested: counting the finger segments of the other four fingers with your thumb gives 12. It's a plausible hypothesis but hard to prove.

12 in the Sky

A solar year contains a little more than 12 lunations (full Moon cycles of about 29.5 days each). That's the origin of the 12 months in many calendars. The zodiac likewise divides the Sun's apparent path into 12 signs of 30 degrees.

The Babylonians counted in base 60, a number divisible by 12 (60 = 5 × 12). Our 60 minutes, 60 seconds and 360-degree circle come from that legacy.

The 12 Hours

The ancient Egyptians divided day and night into 12 hours each, which gave us 24 hours. Originally, these hours varied in length with the seasons.

12 in Stories

• The 12 apostles in Christianity, the 12 tribes of Israel in the Bible.

• The 12 Olympian gods in Greek mythology.

• The 12 labors of Hercules.

12 in Numerology

In numerology, 12 reduces to 3 (1 + 2). Tradition reads it as expression (3) born of initiative (1) and cooperation (2). It's also the digit sum of the universal year 2028 (2 + 0 + 2 + 8 = 12 → 3). For a birthday, see born on the 12th.

Frequently asked questions