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Roman Numeral Converter

Convert any number to Roman numerals or decode a numeral back — with a complete reference chart and the rules that govern them.

Roman Numeral Converter

Edit either field. Roman numerals use I, V, X, L, C, D and M.

🔒 Nothing you enter is sent anywhere or stored. All processing happens in your browser.

How it works

Roman numerals build numbers from seven letters — I (1), V (5), X (10), L (50), C (100), D (500) and M (1000) — combined by addition, with a smaller symbol before a larger one meaning subtraction (IV is 4, IX is 9). The classic system covers 1 to 3999, which is exactly the range this converter handles.

Enter a whole number in the left field to see its Roman form, or type a numeral on the right to decode it back to a number. The two fields are linked, so editing one fills in the other. The numeral field auto-uppercases as you type, and decoding checks that the numeral is well formed — MMXXIV is accepted, but scrambled or repeated forms like IIII or VX are flagged as invalid.

This is useful for reading clock faces, book chapters, movie sequels, monument dates and outlines. Numbers outside 1–3999, or malformed numerals, produce a clear error instead of a guess.

Examples

Number 2024 → MMXXIV.
Numeral MCMLIV → 1954.
Number 4 → IV (subtractive form, not IIII).
Numeral IIII → error, because it is not a valid form.

Roman numerals chart

1–20

NumberRomanNumberRoman
1I11XI
2II12XII
3III13XIII
4IV14XIV
5V15XV
6VI16XVI
7VII17XVII
8VIII18XVIII
9IX19XIX
10X20XX

Tens, hundreds & thousands

NumberRomanNumberRoman
30XXX300CCC
40XL400CD
50L500D
60LX600DC
70LXX700DCC
80LXXX800DCCC
90XC900CM
100C1000M
200CC2000MM

Common years

YearRoman
1990MCMXC
2000MM
2010MMX
2024MMXXIV
2025MMXXV
2026MMXXVI

Frequently asked questions

What range is supported?
Standard Roman numerals from 1 to 3999. There is no symbol for zero, and larger numbers need overlines that fall outside this tool.
Does it check that a numeral is valid?
Yes. Decoding uses a strict pattern, so malformed numerals like IIII, IC or VX are rejected rather than silently accepted.
Is lower case accepted?
Yes. The numeral field is treated case-insensitively and shown in uppercase, so mcmliv works the same as MCMLIV.
Why is 4 written IV and not IIII?
Standard notation uses the subtractive rule, placing a smaller symbol before a larger one, so 4 is IV and 9 is IX.
Does this run offline?
Yes. All conversion happens in your browser with no network requests, so it works even without a connection once loaded.
What are the seven Roman numeral symbols?
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, and M = 1,000. Every Roman numeral is built by combining these seven letters according to a few placement rules.
How does subtractive notation work?
When a smaller symbol appears before a larger one, you subtract it: IV = 4 (5−1), IX = 9, XL = 40, XC = 90, CD = 400, CM = 900. Only I, X and C are used this way, and only before the next one or two larger symbols.
What is the largest number in standard Roman numerals?
Standard Roman numerals go up to 3,999 (MMMCMXCIX). Larger numbers historically used a bar over a numeral to multiply it by 1,000, but that isn't part of the everyday system.
How do I write the current year in Roman numerals?
Break the year into thousands, hundreds, tens and units and convert each. For example 2026 = MM (2000) + XX (20) + VI (6) = MMXXVI. The chart below lists common years.
Is there a zero in Roman numerals?
No. The Roman system has no symbol for zero — it wasn't needed for counting and tallying, which is what the numerals were designed for.