Roman Numerals: The Rules, a Chart and How to Convert Any Number

Roman numerals use seven letters: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1,000. Write the values from largest to smallest and add them up, except that a smaller symbol placed before a larger one is subtracted: IV is 4 and IX is 9. So 2026 is MMXXVI (1,000 + 1,000 + 10 + 10 + 5 + 1), and 2027 is MMXXVII.

The free Roman numeral converter turns any whole number from 1 to 3999 into Roman numerals. It works in one direction only and doesn't read a Roman numeral back into a number, so this guide also shows how to do that by hand, which takes a few seconds once you know the rules. It covers why 3999 is the limit, why clocks show IIII, and where you will meet Roman numerals in India.

The seven symbols

The three rules

1. Add when the values stay the same or go down. VIII = 5 + 1 + 1 + 1 = 8; LXX = 50 + 10 + 10 = 70; MDC = 1,000 + 500 + 100 = 1,600.
2. Repeat I, X, C and M at most three times in a row. V, L and D never repeat, because VV would simply be X.
3. Subtract when a smaller symbol comes before a larger one, but only in six pairs: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). I goes only before V and X, X only before L and C, and C only before D and M.

Rule 3 is where most mistakes happen. 99 is XCIX (90 + 9), not IC; 49 is XLIX (40 + 9), not IL; and 1999 is MCMXCIX, not MIM. You can subtract only I, X or C, and only from the next two symbols up.

Why 4 is IV, not IIII (except on clocks)

Under the standard modern rules, four of the same symbol in a row is not allowed, so 4 is IV and 40 is XL. The Romans themselves were not so strict, and additive forms such as IIII appear in ancient inscriptions; the subtractive forms became the standard later.

Clock faces are the famous exception: many clocks and watches with Roman numerals show 4 as IIII while still showing 9 as IX. Explanations range from visual balance with the VIII opposite to plain tradition, and nobody knows for certain. Either way, it is a clock-face convention, not a different rule for writing numbers. Everywhere else, use IV.

Converting a number to Roman numerals

Work from the largest value down, using this list of 13 values: 1,000 (M), 900 (CM), 500 (D), 400 (CD), 100 (C), 90 (XC), 50 (L), 40 (XL), 10 (X), 9 (IX), 5 (V), 4 (IV) and 1 (I). Take the largest value that fits, write its symbol, subtract it, and repeat. This is exactly how the converter works. Example, 1984:

1. 1,000 fits: write M, leaving 984.
2. 900 fits: write CM, leaving 84.
3. 50 fits: write L, leaving 34.
4. 10 fits three times: write XXX, leaving 4.
5. 4: write IV. Result: MCMLXXXIV.

The converter gives MCMLXXXIV too. It rejects 0, negative numbers and anything above 3999 with the message "Enter 1–3999", and it drops any decimal part without rounding, so 12.7 becomes XII.

Reading a Roman numeral

Go from left to right. If a symbol is smaller than the one after it, subtract it; otherwise add it. Example, MCMXLVII:

• M = 1,000
• CM = 1,000 − 100 = 900
• XL = 50 − 10 = 40
• VII = 5 + 1 + 1 = 7

Total: 1,000 + 900 + 40 + 7 = 1947, the year of India's independence. To check your answer, type the number into the converter and see whether it gives back the same letters.

Why 3999 is the limit, and how bigger numbers were written

The largest number you can write with the standard rules is 3999, MMMCMXCIX. 4,000 would need MMMM, four Ms in a row, and there is no standard symbol above M. That is why the converter, like most others, stops at 3999. There is no Roman numeral for zero at all, which is why it starts at 1.

For bigger numbers, a bar drawn over a numeral (a vinculum) multiplies it by 1,000: V with a bar is 5,000, X with a bar is 10,000 and M with a bar is 1,000,000, so 4,000 can be written as IV with a bar over it. You will rarely need this outside history books, and the converter doesn't produce it.

Roman numeral chart

3888 has the longest standard Roman numeral, at 15 letters.

Where you will see Roman numerals

• School classes and college courses. Classes are often written as Class IX, X, XI and XII (CBSE's own notices say "class X" and "class XII"), and college papers as Semester IV or Part II.
• The Constitution and other legal texts. The Constitution of India is divided into Parts numbered in Roman numerals: Part III covers the Fundamental Rights and Part IV the Directive Principles of State Policy.
• Books. Chapters, volumes and appendices, and the preface pages, which are usually numbered in small letters (i, ii, iii) so that page 1 can start with the first chapter.
• Films and sequels. Rocky II and The Godfather Part II are classic examples, and Mani Ratnam's two-part Tamil epic was released as Ponniyin Selvan: I (2022) and Ponniyin Selvan: II (2023). Film credits often give the copyright year in Roman numerals too.
• The Super Bowl. American football's championship game is numbered in Roman numerals: Super Bowl LX was played on 8 February 2026, and Super Bowl LXI is due in February 2027. The exception was Super Bowl 50 in 2016, which the NFL branded with ordinary digits, partly because a logo built around a single L was hard to design well.
• Kings, queens and popes. Charles III, Elizabeth II, Pope Leo XIV.
• Question papers and lists. Sub-questions numbered (i), (ii), (iii), and outline headings.

When you type Roman numerals, use the ordinary capital letters I, V, X, L, C, D and M. Unicode also has special one-character Roman numerals (such as Ⅻ), but search and forms may not recognise them, and they look different from font to font. For other number formats, the number to words converter writes amounts out in words for cheques and forms (see how to convert numbers to words), and the number base converter handles binary and hexadecimal.

Frequently asked questions

What is 2026 in Roman numerals?

MMXXVI: MM (2,000) + XX (20) + VI (6). 2027 is MMXXVII.

Can the converter turn Roman numerals into numbers?

No. It converts numbers from 1 to 3999 into Roman numerals only, and its box accepts numbers, not letters. Use the left-to-right method above to read a numeral, then check your answer by converting it back.

Is there a Roman numeral for zero?

No. The Roman system has no zero, which is why the converter starts at 1.

How do you write 4,000 or 5,000 in Roman numerals?

With a bar over the numeral, which multiplies it by 1,000: IV with a bar is 4,000 and V with a bar is 5,000. Standard Roman numerals without bars stop at 3999.

Why is 9 written IX and not VIIII?

The standard rules don't allow four of the same symbol in a row, so 9 is written as one less than ten: IX. Even clocks that use IIII for 4 normally show IX for 9.

Sources: NFL announcement on Super Bowl 50 branding (June 2014); Constitution of India (Parts III and IV); Central Board of Secondary Education, "Question Answers with Controller of Examinations" (February 2025).