Why Do Clocks Go Clockwise?

“Clockwise” is defined by clocks — but why did clocks choose that direction in the first place? The answer is older than any clock: the Sun.

Sundials first

For thousands of years people told time with sundials. In the northern hemisphere, where most early mechanical-clock makers lived, the Sun rises in the east, swings across the southern sky and sets in the west. A sundial’s shadow therefore moves around the dial from left to right — the direction we now call clockwise.

Clocks copied sundials

When mechanical clocks appeared in medieval Europe, people already read time by a shadow moving that way. Making the new hand move the same way kept time-telling familiar. After a few centuries, it was simply how clocks worked.

What if clocks had been invented in the south?

In the southern hemisphere, a sundial’s shadow moves the other way. Had clocks been developed there first, “clockwise” might mean the opposite.

The rebels

A few clocks deliberately run backwards. One famous example is on the Jewish Town Hall in Prague, whose Hebrew-numeral dial runs anticlockwise, matching the right-to-left direction of Hebrew writing. Novelty “backwards clocks” are sold as jokes for people who like a challenge.

More quick ones in Wacky Facts.