How to convert a number to Roman numerals
Both directions convert live as you type, so there is no submit button:
- Type a number in the left field, for example 2026, and the Roman numeral appears instantly (MMXXVI).
- Commas and spaces are ignored, so 1,969 and 1969 both work.
- Use the copy button inside each field to copy the value to your clipboard.
- The step-by-step breakdown table shows every symbol, its value and the running total.
How to convert Roman numerals to a number
You can also start from the Roman side:
- Type a Roman numeral in the right field, for example MCMXCIV, and the number appears instantly (1,994).
- Lowercase input is accepted — type mmxxvi and you still get 2,026.
- Spaces, dots and dashes between symbols are removed automatically, so M CM XC IV also works.
- Unicode Roman numeral characters (Ⅰ, Ⅻ, Ⅿ…) are recognised and converted too.
- Invalid numerals such as IIII, VV, IC or VX are rejected with an explanation instead of returning a wrong answer.
Working with numbers above 3,999
Classical Roman numerals only reach 3,999 with the seven basic symbols. For larger values this tool uses overline notation, where a bar over a symbol multiplies it by 1,000. Keep the checkbox enabled and type 4000 to get I̅V̅, or 1,000,000 to get M̅. Uncheck it if you only want classical output up to 3,999.
How Roman numerals work
The Roman numeral system uses seven symbols: I (1), V (5), X (10), L (50), C (100), D (500) and M (1,000). Values are written by placing symbols side by side and adding them up: MMXXVI = 1,000 + 1,000 + 10 + 10 + 5 + 1 = 2,026. When a smaller symbol appears before a larger one it is subtracted instead of added — this is subtractive notation, and the six allowed pairs are IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). The system is not strictly positional like our decimal numbers, which is why the same value can look very different in length: 8 is VIII (five symbols) while 1,888 is MDCCCLXXXVIII, one of the longest numerals in the classical range.
The rules a valid Roman numeral must follow
Not every string of Roman symbols is a valid numeral. The rules are: (1) symbols are usually written from largest to smallest; (2) I, X, C and M may repeat up to three times in a row, but V, L and D never repeat at all; (3) only I, X and C can be used as subtractive symbols, and only in the six pairs IV, IX, XL, XC, CD and CM — so IC (99) and IL (49) are invalid even though they look convenient; (4) subtracting from a symbol more than one step away is not allowed. This tool applies all four rules, which is why it rejects IVI, XXXX, MMMM is accepted as the traditional 4,000 spelling, and why popular mistakes like IIII for 4 are caught.
Large numbers and overline notation
To go beyond 3,999, Roman writers used a bar (vinculum) over a symbol to multiply it by 1,000: V̅ = 5,000, X̅ = 10,000, L̅ = 50,000, C̅ = 100,000, D̅ = 500,000 and M̅ = 1,000,000. Combining the bar with subtractive pairs gives very large values compactly: 4,000 is I̅V̅, and 1,234,567 is M̅C̅C̅X̅X̅X̅I̅V̅DLXVII. Some ancient sources used alternative notations such as apostrophus (ↀ for 1,000, ↁ for 5,000) or a box around the numeral, but the overline system is the one still taught in mathematics classes today. Modern use rarely needs these values: years, chapter numbers, film sequels, clock faces, Super Bowl numbering and copyright dates all stay comfortably below 4,000.
Where Roman numerals are still used
Roman numerals appear in more places than people expect. They mark publication years in film and TV credits (MMXXVI for 2026), number Super Bowls and Olympic Games, name monarchs and popes (Elizabeth II, John XXIII), label chapters and volumes in books, label clock faces, and are used in outlines and legal documents. They are also common in tattoo designs and on building cornerstones. Because the symbol inventory is tiny and the conversion is pure arithmetic, everything on this page runs in your browser with no data sent anywhere.
Frequently Asked Questions (FAQs)
How do I write 2026 in Roman numerals?
2026 is MMXXVI: M + M + X + X + V + I = 1,000 + 1,000 + 10 + 10 + 5 + 1. Type 2026 in the number field and the converter shows it instantly, along with the full breakdown of each symbol.
What is the largest number I can convert?
You can convert any number from 1 to 3,999,999. Values up to 3,999 use the seven classical symbols, and larger values use overline notation where a bar multiplying a symbol by 1,000 (V̅ = 5,000, M̅ = 1,000,000).
Why is 4 written as IV and not IIII?
Subtractive notation replaces four repeated symbols with a smaller symbol before a larger one: IIII becomes IV (5 − 1). The same idea gives IX for 9, XL for 40, XC for 90, CD for 400 and CM for 900. IIII still appears on some clock faces for visual symmetry opposite VIII, but IV is the standard form, and this converter follows the standard.
Is IC a valid way to write 99?
No. Subtractive notation only allows I before V and X, X before L and C, and C before D and M. So 99 must be written XCIX (90 + 9), not IC, and 49 must be written XLIX, not IL. This tool rejects IC, IL, VD and similar short forms.
What does the bar over a Roman numeral mean?
A bar (called a vinculum) multiplies the symbol underneath by 1,000. So V̅ equals 5,000 and M̅ equals 1,000,000. For example, 4,000 is written I̅V̅ and 12,000 is X̅I̅I̅. The converter can output and read this overline notation, and you can turn it off if you only need classical numerals.
Does the converter send my input to a server?
No. All conversions happen locally in your browser using JavaScript. Nothing you type is transmitted, logged or stored, so the tool is safe for dates, contract clauses and any other sensitive numbers.
Can I convert Roman numerals in lowercase or with spaces?
Yes. Input is case-insensitive, so mmxxvi is read as MMXXVI, and common separators such as spaces, dots, commas and dashes are stripped before validation — M CM XC IV becomes MCMXCIV = 1,994. Unicode Roman numeral characters such as Ⅻ and Ⅿ are also accepted.
