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Why Do Clocks Use IIII Instead of IV?

March 9, 2026

The IIII Mystery

Look at almost any clock or watch with Roman numerals and you'll notice something peculiar: the number 4 is written as IIII, not IV. This contradicts the standard rules of Roman numerals, where a smaller value before a larger value means subtraction. By every textbook, 4 should be IV. Yet clockmakers have used IIII for centuries — and most still do today.

This is one of the most frequently asked questions about Roman numerals, and it has no single definitive answer. Instead, there are several compelling theories, each with historical support.

The Leading Theories

Visual Balance and Symmetry

The most widely accepted explanation is aesthetic. Look at a clock face divided into three visual groups:

  • Left side (I-group): I, II, III, IIII — four entries using only the symbol I
  • Bottom (V-group): V, VI, VII, VIII — four entries using V and I
  • Right side (X-group): IX, X, XI, XII — four entries using X and I

With IIII instead of IV, each group contains exactly four numerals, and the visual weight is distributed evenly around the dial. If you used IV, the left group would have only three entries, and it would visually "belong" to the V-group, breaking the symmetry. This theory is particularly convincing because clockmakers are craftspeople deeply concerned with visual harmony.

The Jupiter Theory

An intriguing historical theory involves the king of the Roman gods. In Latin, Jupiter is spelled IVPPITER (or IUPPITER). Some historians suggest that ancient Romans avoided using IV out of reverence — it would mean placing the first two letters of Jupiter's name on a mundane counting device. While this theory is difficult to verify, it's consistent with Roman religious practices that prohibited casual use of divine names.

The Illiterate Masses Theory

In medieval Europe, when the first public tower clocks appeared, most of the population could not read. Subtractive notation (IV, IX) is more cognitively demanding than simple additive counting (IIII). Some scholars argue that IIII was used because it was easier for ordinary people to count four strokes than to understand the subtraction principle. This theory has some holes — clocks still use IX for 9 — but it may have been a contributing factor.

The Casting Theory

A practical explanation from clockmaking: when casting metal numerals for a clock face, using IIII instead of IV reduces the number of unique molds needed. With IIII, you need a mold that produces twenty I's, four V's, and four X's — which can be efficiently cast as four identical sets of VIIII from a single mold. Using IV would require a different arrangement and additional complexity in the casting process.

King Charles V Theory

One popular legend attributes the convention to King Charles V of France (14th century), who allegedly ordered his clockmaker to use IIII because he insisted that IV was incorrect. While this story is widely repeated, there is little documentary evidence to support it, and IIII on clock faces predates Charles V.

Clocks That Use IV

Not all clocks use IIII. A notable exception is the Great Clock of Westminster (commonly called Big Ben), which displays IV rather than IIII on its dial. Several other prestigious clocks also use IV:

  • Big Ben (Palace of Westminster, London) — uses IV
  • The Shepherd Gate Clock (Royal Greenwich Observatory) — uses IV
  • Many Breguet watches — historically used IV

Some modern watch brands offer both versions, and collectors often have strong preferences. Rolex, for instance, consistently uses IIII on its Roman numeral dials.

Historical Context

The use of IIII predates mechanical clocks entirely. Ancient Roman sundials and inscriptions frequently show IIII rather than IV. The subtractive notation that gives us IV was not standardized until relatively late in the Roman era — and even then, both forms coexisted. The Colosseum in Rome, for example, has entrance gates numbered with both IIII and IV in different sections.

So the "correct" form for 4 in Roman numerals has never been as settled as modern textbooks suggest. Clockmakers didn't break a rule; they preserved an older tradition. For more on how Roman numeral rules developed, see our history of Roman numerals.

Why It Still Matters

The IIII convention persists because it works. Clock faces are a living tradition, and IIII is now so deeply embedded that changing to IV would look wrong to most people. This is a beautiful example of how practical design choices can outlast the technical rules they appear to violate.

Next time you glance at a clock with Roman numerals, check whether it uses IIII or IV. You'll find that IIII dominates overwhelmingly — and now you know the reasons why.

If you're curious about the broader system, our complete guide to Roman numerals covers all the rules and exceptions.

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