How to Read and Write Roman Numerals

Roman numerals have been around for over two thousand years, and they are still everywhere: clock faces, movie credits, Super Bowl logos, book chapter headings, building cornerstones, and formal outlines. Despite their age, they follow a logical set of rules that anyone can learn in a few minutes.

This guide teaches you the rules for reading and writing Roman numerals, explains the subtractive notation that trips people up, and covers the places you will encounter them in everyday life.

The Seven Basic Symbols

The entire Roman numeral system uses just seven letters, each representing a fixed value:

Symbol	Value
I	1
V	5
X	10
L	50
C	100
D	500
M	1,000

Every Roman numeral is built by combining these symbols according to two main rules: addition and subtraction.

Rule 1: Addition (Left to Right)

When symbols are arranged from largest to smallest (left to right), you add their values together.

VI = 5 + 1 = 6
XV = 10 + 5 = 15
LXI = 50 + 10 + 1 = 61
MDCLXVI = 1000 + 500 + 100 + 50 + 10 + 5 + 1 = 1,666

You can repeat I, X, C, and M up to three times in a row:

III = 3
XXX = 30
CCC = 300
MMM = 3,000

You can’t repeat V, L, or D. Instead of VV (which would equal 10), you write X. Instead of LL (100), write C.

Rule 2: Subtractive Notation

When a smaller symbol appears immediately before a larger one, you subtract the smaller from the larger. This is the rule that creates the “shorthand” forms for 4, 9, 40, 90, 400, and 900.

Combination	Calculation	Value
IV	5 - 1	4
IX	10 - 1	9
XL	50 - 10	40
XC	100 - 10	90
CD	500 - 100	400
CM	1000 - 100	900

Only these six subtractive combinations are standard. You would never write IC for 99 (the correct form is XCIX: 90 + 9) or VX for 5 (that’s simply V).

The subtractive rule exists to avoid writing four symbols in a row for certain values. Without it, 9 would be VIIII and 40 would be XXXX. The subtractive forms are shorter and have been the convention since the Middle Ages.

Building Any Number Step by Step

To convert a regular number to Roman numerals, break it down by place value and translate each part.

Example: 1,994

1,000 = M
900 = CM
90 = XC
4 = IV
Combined: MCMXCIV

Example: 2,764

2,000 = MM
700 = DCC
60 = LX
4 = IV
Combined: MMDCCLXIV

Example: 3,888 (the longest standard Roman numeral under 4,000)

3,000 = MMM
800 = DCCC
80 = LXXX
8 = VIII
Combined: MMMDCCCLXXXVIII (15 characters!)

The system works well for numbers up to 3,999 (MMMCMXCIX). Beyond that, ancient Romans used bars over letters to indicate multiplication by 1,000, but this notation is rarely needed today.

Reading Roman Numerals

To read a Roman numeral, scan from left to right. When each symbol is equal to or larger than the one following it, add. When a symbol is smaller than the one following it, subtract.

Example: MCMLXXXIV

M = 1,000
CM = 900 (C is smaller than M, so subtract)
L = 50
XXX = 30
IV = 4 (I is smaller than V, so subtract)
Total: 1,000 + 900 + 50 + 30 + 4 = 1,984

Example: CDXLVIII

CD = 400
XL = 40
V = 5
III = 3
Total: 400 + 40 + 5 + 3 = 448

Where You Will See Roman Numerals Today

Clock and Watch Faces

Traditional analog clocks use Roman numerals on their dials. Interestingly, most clocks use IIII for 4 rather than the standard IV. There are several theories for this: visual symmetry with VIII on the opposite side, tradition dating back to early clockmakers, or the practical reason that IIII is easier to read upside down at the 4 o’clock position.

Movies and Television

Film and TV production years are traditionally shown in Roman numerals in the end credits. A movie from 2025 shows MMXXV. This practice dates to the early days of cinema and persists as a stylistic tradition, though some modern productions have switched to standard digits.

Super Bowl Numbering

The NFL has used Roman numerals for Super Bowl names since Super Bowl V in 1971. Super Bowl LVIII (58) took place in 2024. The single exception was Super Bowl 50, where the league used an Arabic numeral because the “L” alone was considered insufficiently dramatic for marketing.

Outlines and Numbering

Formal outlines, legal documents, and academic papers use Roman numerals for major sections:

I. Introduction
   A. Background
   B. Purpose
II. Methods
   A. Data Collection
   B. Analysis
III. Results

Upper-case Roman numerals mark the highest level, with lowercase Roman numerals (i, ii, iii) sometimes used for sub-sections.

Building Dates and Cornerstones

Buildings often display their construction year in Roman numerals on cornerstones or facades. A building marked MCMXLVII was built in 1947.

Royalty and Popes

Monarchs and popes with the same name are distinguished by Roman numerals: Queen Elizabeth II, Pope John XXIII, King Charles III. The numeral follows the name with no comma.

Page Numbering in Books

Many books use lowercase Roman numerals (i, ii, iii, iv) for front matter (preface, table of contents, acknowledgments) and switch to Arabic numerals for the main text. This allows the main text to always start on “page 1” regardless of how long the front matter is.

Common Mistakes

Using Subtractive Notation Incorrectly

Only the six standard subtractive pairs are valid. Common errors include:

IC for 99: Should be XCIX (90 + 9)
XM for 990: Should be CMXC (900 + 90)
VL for 45: Should be XLV (40 + 5)

Repeating V, L, or D

These symbols are never repeated. VV isn’t valid for 10 (use X). LL isn’t valid for 100 (use C).

Exceeding Three Repetitions

I, X, C, and M can each appear a maximum of three times consecutively. IIII is technically nonstandard (except on clock faces), and XXXX never appears. If you find yourself writing four of the same symbol, you need the subtractive form (IV, XL, CD) or the next larger symbol.

Quick Reference for Common Numbers

Number	Roman	Number	Roman
1	I	50	L
4	IV	90	XC
5	V	100	C
9	IX	400	CD
10	X	500	D
14	XIV	900	CM
19	XIX	1,000	M
40	XL	2,024	MMXXIV

Use the Tool

For quick conversions in either direction, our Roman Numeral Converter handles the translation instantly. Enter a standard number and get the Roman numeral form, or enter Roman numerals and get the decimal value. It is particularly useful for verifying movie years, building dates, or outline numbering.

Frequently Asked Questions

What is the largest number you can write in standard Roman numerals?

The largest number using standard notation (without special extensions) is 3,999, written as MMMCMXCIX. To write larger numbers, the Romans placed a bar (called a vinculum) over a numeral to multiply its value by 1,000. So a V with a bar over it equals 5,000 and an X with a bar equals 10,000. This extended notation is rarely used today.

Is there a Roman numeral for zero?

No. The Roman numeral system has no symbol for zero. The concept of zero as a number was not part of Roman mathematics. It was introduced to European mathematics from Arabic and Indian numeral systems around the 12th and 13th centuries. Roman numerals are used for counting, ordering, and labeling, which historically did not require a zero.

Why do clocks use IIII instead of IV?

The most accepted explanation is visual balance. Using IIII creates a symmetrical arrangement with VIII on the opposite side of the dial. Each third of the clock face then contains four numerals using only I (first third: I, II, III, IIII), only V and I (second third: V, VI, VII, VIII), and only X and I (third third: IX, X, XI, XII). Some historians also attribute the practice to King Louis XIV of France, who supposedly preferred IIII, though this story is debated.

How were Roman numerals used for math calculations?

They were not well suited for arithmetic. Romans relied on counting boards (abacuses) for calculations and used numerals primarily for recording results. Addition and subtraction are manageable with Roman numerals, but multiplication and division are extremely difficult. This limitation is a key reason Arabic numerals eventually replaced them for mathematical purposes.

Can Roman numerals represent fractions or decimals?

The Romans did have a system for fractions, but it was based on twelfths rather than tenths. The basic fraction unit was the uncia (one-twelfth), from which the English word “ounce” derives. Six unciae equaled one-half, represented by the letter S (for semis). This system is completely obsolete today, and modern uses of Roman numerals are limited to whole numbers.