Curiosity · Clock faces & IIII

Roman Numerals on Clocks

Q: Why do clocks use IIII instead of IV?

It is a long-standing horological tradition. The leading explanations are visual balance with VIII opposite, easier mould casting of identical I-castings, and avoiding IV as it resembled the start of the Roman god Jupiter's name (IVPITER).

Q: Is IIII correct on a clock?

On a clock face IIII is the accepted traditional form. In standard mathematical notation, four is always IV.

Q: What are the clock numerals 1 to 12?

I, II, III, IIII, V, VI, VII, VIII, IX, X, XI, XII — with IIII used instead of IV by tradition.

Updated: June 2026

Look at almost any classic clock face and you will spot something that breaks the rules: four o'clock is marked IIII, not IV. It is one of the most charming quirks in the history of timekeeping, and there is no single agreed reason for it — just a handful of persuasive theories that have outlived the watchmakers who started the habit.

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The clock dial in full

A Roman clock face counts the twelve hours like this:

Hour	Numeral	Hour	Numeral
1	I	7	VII
2	II	8	VIII
3	III	9	IX
4	IIII	10	X
5	V	11	XI
6	VI	12	XII

Notice 9 is still the standard subtractive IX — only the 4 gets the special treatment. That asymmetry is exactly what makes the IIII question so interesting.

Theory 1 — visual balance

The most popular explanation is symmetry. Split the dial into three groups of four hours. Using IIII for the fourth hour means the left side of the dial is built only from I shapes, the bottom mixes in V, and the right side introduces X. The numeral VIII sits directly opposite IIII, and the two heavy, multi-stroke numerals balance each other visually. Swapping in a slim IV would make that side look lighter and lopsided.

Theory 2 — easier casting

Before numerals were printed, they were often cast or cut from metal. If you make the twelve hours from repeated moulds, using IIII lets a clockmaker produce every numeral from just three master shapes: a strip of Is, a V and an X. The total count of each symbol also comes out neat — twenty Is, four Vs and four Xs — which a workshop could batch efficiently. An IV at four o'clock would spoil that tidy arithmetic.

Theory 3 — respect for Jupiter

A more romantic theory points to ancient Rome itself. In classical Latin the king of the gods, Jupiter, was written IVPITER — beginning with the very letters IV. Some argue that early dial-makers avoided IV out of reverence, not wanting to stamp a fragment of the god's name onto an everyday object. Whether or not this drove the original choice, it is a story that has helped the IIII tradition endure.

So which is correct?

On a clock face, IIII is the accepted, traditional form for four o'clock.
In standard notation — dates, page numbers, maths — four is always IV.
A few famous clocks, including the one on the Houses of Parliament, do use IV, so the rule is a convention, not a law.

If you are converting a time for anything other than a decorative dial, stick with IV — and the converter's strict mode will keep you to the standard form.

Frequently asked questions

Why do clocks use IIII instead of IV?

By tradition. The leading reasons are visual balance with VIII opposite, simpler casting from repeated moulds, and historical avoidance of IV as the start of IVPITER.

Is IIII correct?

On a clock, yes. In ordinary notation, four is always IV.

What are the clock numerals 1 to 12?

I, II, III, IIII, V, VI, VII, VIII, IX, X, XI, XII.

Why is 9 still IX on clocks?

The balance and casting reasons specifically favour replacing only the 4; the 9 stays as the standard IX.