Roman Numerals Complete Guide: How to Read, Write & Convert Them

The 7 Roman Numeral Symbols

The entire system is built from just seven letters. Every Roman numeral, from 1 to 3,999, is formed by combining these symbols according to a small set of rules.

Notice that V, L, and D are never repeated — you will not find VV, LL, or DD in any valid Roman numeral. Only I, X, C, and M can repeat, and even then, no symbol appears more than three times in a row.

How to Read Roman Numerals: Additive and Subtractive Rules

Reading a Roman numeral comes down to one key observation: look at whether each symbol is followed by something larger or something smaller (or equal).

The Additive Rule

When symbols are arranged from largest to smallest, left to right, you simply add them up.

• VII = 5 + 1 + 1 = 7
• LX = 50 + 10 = 60
• MDCII = 1000 + 500 + 100 + 1 + 1 = 1602

The Subtractive Rule

When a smaller symbol appears before a larger one, you subtract the smaller value from the larger. This is subtractive notation, and it exists to avoid awkward runs of four identical symbols.

• IV = 5 − 1 = 4 (not IIII)
• IX = 10 − 1 = 9 (not VIIII)
• XL = 50 − 10 = 40
• XC = 100 − 10 = 90

The 6 Subtractive Pairs You Need to Know

Only six specific subtractive combinations are valid in standard Roman numerals. Anything else (such as IC for 99 or VX for 5) is not accepted in classical notation.

The rule behind each pair: only I, X, and C can be used subtractively, and each can only precede the two symbols directly above it. I can precede V (5) and X (10). X can precede L (50) and C (100). C can precede D (500) and M (1000).

How to Write Any Number in Roman Numerals (Step by Step)

The method is the same every time: break the number into its thousands, hundreds, tens, and ones, then convert each group using the table below.

Example 1: 2024 (MMXXIV)

• 2000 = MM
• 0 hundreds = (nothing)
• 20 = XX
• 4 = IV
• Result: MMXXIV

Example 2: 1999 (MCMXCIX)

• 1000 = M
• 900 = CM
• 90 = XC
• 9 = IX
• Result: MCMXCIX

Example 3: 42 (XLII)

• 0 thousands = (nothing)
• 0 hundreds = (nothing)
• 40 = XL
• 2 = II
• Result: XLII

Roman Numerals 1–20 Reference Table

Where Roman Numerals Still Appear Today

Roman numerals never disappeared — they just moved into specific roles where tradition or prestige matters.

• Clock faces: Many analog clocks use Roman numerals for the hours, with one quirk — some clock manufacturers write IIII instead of IV for 4, because it looks more balanced on the dial.
• Movie and TV sequels: Film studios have used Roman numerals for decades. Rocky II, Star Wars Episode IV, Rocky IV, Fast X. HBO uses them for episode and season numbering in title cards.
• The Super Bowl: The NFL has used Roman numerals since Super Bowl V (1971). Super Bowl LIX was played in 2025.
• Copyright years: Many production companies and broadcasters still display copyright dates in Roman numerals at the end of programs. MCMXCIX (1999) was the last year this was common before many switched back to Arabic.
• Book chapters and front matter: Academic books typically number their preface, introduction, and table of contents pages in Roman numerals (i, ii, iii...) while the main text uses Arabic numerals.
• Monarchs and popes: Henry VIII, Elizabeth II, Pope Francis I. The numeral distinguishes one ruler from another with the same name.
• Chemistry and periodic table: Group numbers in older IUPAC notation used Roman numerals (Group IA, IIA, etc.). Oxidation states are also written in Roman numerals: Fe(III), Cu(II).
• Building cornerstones and monuments: Many buildings inscribe their construction year in Roman numerals — look at the base of statues or the keystones of arched entrances.

What Roman Numerals Cannot Represent

The Roman system has real limitations that eventually led to the adoption of Hindu-Arabic numerals in medieval Europe.

• Zero: There is no symbol for zero. The Romans had the concept (the Latin word nulla), but it was never part of the numeral system. This made arithmetic with large numbers extremely slow.
• Fractions: Standard Roman numerals only represent whole numbers. The Romans did have a separate fractional system based on twelfths (using dots and S for half), but it never merged with the letter-based numerals.
• Negative numbers: No representation exists. The system was designed for counting and recording, not for algebra.
• Numbers above 3,999: In classical notation, the largest representable number is MMMCMXCIX (3,999). A bar over a symbol (vinculum) was used in some manuscripts to multiply by 1,000, but this is rarely seen or accepted today.

These limitations explain why Roman numerals work well as labels (chapter numbers, years, rankings) but not for calculation. When you need to multiply MCMXCIX by XLII, the difficulty becomes obvious.