1 in Roman Numerals = I

I is one of the seven symbols the whole system is made from (I, V, X, L, C, D, M), so there is nothing to add and nothing to take away. The stroke is the number.

Everything up to three is this same stroke repeated: I, II, III. At four the repetition stops and the subtractive rule takes over with IV, which is why I never appears four times in a row in a standard numeral.

How I is formed

Reading left to right, 1 breaks into these additive parts. Each Roman symbol is added in turn to reach the total.

I = 1 = 1.

Why 1 is written I

There is no Roman symbol for zero, so I is where counting starts. That absence is not an oversight: the Romans counted objects rather than positions, and a place-value zero was not needed to write a number down. When a Roman-era text did need to record nothing at all, it used the Latin word nulla rather than a symbol.

Where 1 in Roman numerals is used

Clock and watch dials: One o'clock is the I at the upper right of a Roman-numeral dial, the first mark clockwise from XII.
Book front matter: The pages before a book's first chapter are numbered in lower-case Roman numerals, so page i is the very first page of the front matter and Arabic 1 only starts at the opening of the main text.
Regnal names: A monarch is only ever called the First once a second of the same name exists. Elizabeth I of England was simply Elizabeth in her own lifetime, and the I was applied afterwards, once Elizabeth II made the distinction necessary.
Super Bowl I: The first NFL championship under the Super Bowl name, played in January 1967, is retroactively known as Super Bowl I. It was not billed with a numeral at the time either.

Common mistakes writing 1 in Roman numerals

0 is wrong. Standard Roman numerals have no symbol for zero, so there is nothing below I. Converters that accept 0 are inventing a form that never existed.
i is wrong. Lower case is correct in book front matter and in some outline styles, but the standard written form of the numeral is the capital I.

Good to know about 1

On a clock or watch face, 1 o'clock is shown as I.
Super Bowl I was played in 1967; the NFL numbers its championship in Roman numerals (with the one-off exception of Super Bowl 50).

Convert another number

Frequently asked questions

Why is there no Roman numeral for zero?

The Roman system counts quantities rather than filling place-value slots, so it never needed a symbol meaning empty. Latin used the word nulla when nothing had to be recorded, and I remains the smallest numeral you can write.

How do you write 1 in Roman numerals?

Write 1 as I, combining I. Start from the largest value that fits and work down until nothing is left over.

Is I the 1 you see on a clock?

Yes. 1 o'clock is written I on Roman-numeral clock and watch faces, with the one quirk that many dials print four as IIII rather than IV out of tradition.

Which Super Bowl is I?

Super Bowl I is the 1st Super Bowl, played in 1967. The NFL sets its championship number in Roman numerals, which is why so many people look up values like I.

What number is I?

I is 1. Read the symbols left to right, treat any smaller-before-larger pair as a single subtraction, and add the groups together.