Guide

Why clocks use IIII instead of IV

By Mark · Updated 26 October 2026

Ask anyone how to write four in Roman numerals and they'll say IV. Yet look at almost any clock with Roman numerals and you'll see IIII. It's called the clockmaker's four, and nobody knows for certain how it started. These are the explanations people give most often.

The eastern clock face of the Zytglogge tower in Bern, with gold Roman numerals on a dark dial; four o'clock is written IIII. — The Zytglogge clock in Bern, Switzerland. Four o'clock is written **IIII**, in the clockmaker's tradition. Photo: Sandstein, Public domain, via Wikimedia Commons.

It balances the dial

This is the most practical reason. On a dial, IIII sits opposite VIII, the heaviest numeral on the face. IIII has four strokes and VIII has four characters, so the two sides look evenly weighted. IV would leave the right-hand side looking light.

There's a neater pattern too. With IIII, the first four hours use only I, the next four (V to VIII) all start with V, and the last four (IX to XII) all include X. The dial falls into three tidy groups.

The Romans wrote it that way too

The strict rule that four must be IV came much later. Roman inscriptions often use additive forms such as IIII and VIIII alongside subtractive ones. Early clockmakers were following a long tradition rather than breaking a rule. More on how subtraction works.

A Roman marble memorial inscription for Claudia Ilias. The last line reads VIXIT ANNIS XXXXVII M I DIEB II. — A Roman memorial to Claudia Ilias. The last line, **VIXIT ANNIS XXXXVII**, says she lived 47 years, with 40 written XXXX rather than XL. Photo: Mark Landon, CC BY 4.0, resized, via Wikimedia Commons.

It made casting easier

A popular story says numerals were cast in metal from a set of moulds. With IIII, the twelve hours need exactly twenty I's, four V's and four X's, which divide neatly into four identical sets: one mould could be used four times. With IV, the counts don't divide so evenly. The arithmetic is right; whether clockmakers actually worked this way is less certain.

A legend about Jupiter

In Latin, Jupiter was written IVPPITER or IVPITER, starting with the letters IV. A well-known legend says the Romans avoided IV out of respect for the god. It's a good story, but there's little evidence for it.

Not every clock follows the rule

The clockmaker's four is a tradition, not a law. The dials of the Great Clock of Westminster, the clock in the Elizabeth Tower usually called Big Ben, show IV. Many modern watches use IV too. Both are correct; IIII simply looks more like a clock to most people.

Close-up of a Great Clock of Westminster dial, photographed in 2009, with Gothic Roman numerals; four o'clock is written IV. — A dial of the Great Clock of Westminster (Big Ben), photographed in 2009. Here four o'clock is IV. Photo: Ermell, CC BY-SA 4.0, resized, via Wikimedia Commons.

Which should you use?

For a clock face, including a clock tattoo, IIII looks traditional and balanced.
For anything else, such as a date, a number or a year, use IV. IIII outside a clock face looks like a mistake.

The clock face generator uses IIII by default and lets you switch to IV, so you can compare them on the same dial.