Roman numeral converter
Type an Arabic number to get the Roman numeral equivalent, or paste a Roman numeral to decode it back.
51
LI
52
LII
53
LIII
54
LIV
55
LV
56
LVI
57
LVII
58
LVIII
59
LIX
60
LX
61
LXI
62
LXII
63
LXIII
64
LXIV
65
LXV
66
LXVI
67
LXVII
68
LXVIII
69
LXIX
70
LXX
71
LXXI
72
LXXII
73
LXXIII
74
LXXIV
75
LXXV
76
LXXVI
77
LXXVII
78
LXXVIII
79
LXXIX
80
LXXX
81
LXXXI
82
LXXXII
83
LXXXIII
84
LXXXIV
85
LXXXV
86
LXXXVI
87
LXXXVII
88
LXXXVIII
89
LXXXIX
90
XC
91
XCI
92
XCII
93
XCIII
94
XCIV
95
XCV
96
XCVI
97
XCVII
98
XCVIII
99
XCIX
100
C
About this tool
Roman numerals encode value additively with a subtractive shortcut, using seven letters: I, V, X, L, C, D, and M. Symbols are written largest first and added together, except where a smaller symbol precedes a larger one, in which case it is subtracted — IV is four, IX is nine, XL is forty. The subtractive rule is constrained rather than general: only I, X, and C may be subtracted, and only from the next two larger symbols, which is why 99 is XCIX and never IC. The system has no zero and no way to write a negative or a fraction, and because there is no symbol above M, the practical ceiling in standard notation is 3,999. You still meet Roman numerals in book chapters and prefaces, film copyright dates, monarch and pope regnal numbers, Super Bowl numbering, clock faces, and building cornerstones. This tool converts in both directions — enter a number from 1 to 3999 to get the numeral, or enter a numeral to get the number — and shows the breakdown of which symbol contributes which value.
- 1
Enter an Arabic number (1–3999) to convert it to Roman numerals.
- 2
Or enter a Roman numeral (like XIV or MMXXIV) to convert it to an Arabic number.
- 3
The result appears instantly — no button press needed.
Convert a year to Roman numerals for a logo, tattoo, or monument inscription.
Decode Roman numerals on clocks, movie titles, or historical documents.
Check your Roman numeral conversion homework instantly.
Number to Roman
2024MMXXIVNumber to Roman
42XLIIRoman to number
MCMXCIX1999A numeral like IIII or IC is rejected
Cause: Both violate standard notation. A symbol may repeat at most three times, and subtraction is limited to I before V or X, X before L or C, and C before D or M.
Fix: Use IV rather than IIII and XCIX rather than IC. IIII does appear on many clock faces, a traditional exception that standard notation does not otherwise recognise.
Numbers above 3999 will not convert
Cause: Standard Roman notation has no symbol for five thousand or above. Larger values historically used a vinculum — an overbar multiplying a symbol by a thousand — which has no plain-text representation.
Fix: Stay within 1 to 3999. If you genuinely need larger values, they are conventionally written with the overbar notation, which requires markup rather than letters.
A numeral converts to an unexpected number
Cause: Order matters, and a lowercase or mistyped letter changes the value silently. MCM is 1900, but MMC is 2100, and a stray I in the wrong place shifts the result by two rather than one.
Fix: Check the breakdown shown alongside the result to see exactly which symbol contributed which value. Reading the numeral back from the breakdown catches transpositions quickly.
These answers explain common roman numerals tasks, expected input formats, and edge cases so both visitors and search engines can understand what this tool does.
What is the range supported?
Standard Roman numerals cover 1 to 3999. Numbers outside this range cannot be represented with the classic seven-symbol system (I, V, X, L, C, D, M).
What does MMXXIV mean?
MMXXIV is 2024 in Roman numerals. MM = 2000, XX = 20, IV = 4.
Why is 4 written as IV and not IIII?
IV uses the subtractive principle — placing a smaller numeral before a larger one means subtract. IV = 5 − 1 = 4. This rule applies to: IV (4), IX (9), XL (40), XC (90), CD (400), CM (900).
How do I convert a year to Roman numerals?
Enter the year as a number — for example 2025 — and the tool returns the Roman numeral MMXXV. This is useful for copyright notices, monument inscriptions, film titles, and chapter headings.
Can I decode a Roman numeral I found on a clock or building?
Yes. Switch to the Roman → Number direction, type the Roman numeral exactly as you see it, and the tool returns the Arabic integer. The tool also validates the sequence and rejects malformed combinations.