Why Are There 60 Minutes in an Hour?

Almost everything we measure runs on tens. Money, distance, weight — all decimal. Then you look at a clock and the pattern breaks: 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day. Why 60, of all numbers?

The answer is nearly 4,000 years old, and it comes down to a single quirk of arithmetic that made one number far more useful than ten.

The Babylonians counted in 60

The system we still use was inherited from the Babylonians, who built their mathematics on base 60 (a system called sexagesimal) around 2000 BCE. They in turn borrowed it from the earlier Sumerians.

Why would anyone count in 60 instead of 10? Because 60 divides beautifully. It is the smallest number that can be evenly split by 1, 2, 3, 4, 5, and 6 — and also by 10, 12, 15, 20, and 30.

60 has 12 divisors: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60. 10 has only 4: 1, 2, 5, 10.

That matters enormously before calculators exist. A third of an hour is a clean 20 minutes. A quarter is 15. A sixth is 10. Try that with a base-10 hour and a third becomes 33.33… minutes — an ugly, unending fraction. The Babylonians chose the number that made everyday division painless.

From the sky to the clock

Babylonian astronomers also divided the circle into 360 degrees — six sixties — and split each degree into 60 “minutes” and each minute into 60 “seconds.” Those names are not a coincidence.

• Minute comes from the Latin pars minuta prima, the “first small part” of an hour.
• Second comes from pars minuta secunda, the “second small part” — the small part of the small part.

So a second is literally a subdivision twice over. The astronomy came first; clocks borrowed the vocabulary centuries later when they finally became precise enough to need it.

Why 24 hours, not 60?

The day breaks the pattern — it uses 24, not 60. That number came from Egypt, not Babylon. The Egyptians divided daylight into 12 parts (tracked by shadow clocks) and the night into another 12 (tracked by the rising of stars), giving 24 uneven “hours” that stretched and shrank with the seasons.

Fixed-length hours only arrived much later, once mechanical clocks demanded a constant unit. By then the 12-and-12 structure was too entrenched to change — which is also why we still split the day into two 12-hour halves with AM and PM.

The system that refused to die

Decimal time has been tried. During the French Revolution, France introduced a 10-hour day, with 100 minutes per hour and 100 seconds per minute. It was mathematically tidy and lasted about 17 months before being abandoned. People simply would not give up their clocks.

Base 60 survived because it was already everywhere — in navigation, astronomy, and every clock face ever made. The cost of switching always outweighed the benefit.

Doing the conversions

The base-60 structure is why converting time units takes a moment of thought rather than just moving a decimal point:

• 1 hour = 60 minutes = 3,600 seconds (60 × 60)
• 1 day = 24 hours = 1,440 minutes = 86,400 seconds
• Half an hour = 30 minutes = 1,800 seconds

You can run any of these instantly with the minutes converter or the all-in-one Time Unit Converter, which normalizes everything through seconds so the awkward 60s and 24s cancel out for you.

Key takeaways

• We use 60 because the Babylonians did — and 60 has more clean divisors than 10, making mental division easy.
• Minutes and seconds are named as the first and second subdivisions of an hour, borrowed from astronomy.
• The 24-hour day is an Egyptian inheritance, split into 12 day-hours and 12 night-hours.
• Decimal time has been attempted and failed; base 60 was simply too embedded to replace.