Roman Numeral Converter
Convert any whole number from 1 to 3999 into a Roman numeral, or turn a Roman numeral back into a regular number.
Example
The year 2024 converts to MMXXIV (MM = 2000, XX = 20, IV = 4). Going the other way, MCMXCIV decodes to 1994.
How it works
Numbers are built greedily from the largest Roman value down (M=1000, D=500, C=100, L=50, X=10, V=5, I=1) using subtractive pairs like CM (900) and IV (4). Decoding sums each symbol's value, subtracting when a smaller symbol precedes a larger one.
Good to know
This Roman Numeral Converter turns whole numbers from 1 to 3999 into Roman numerals and decodes Roman numerals back into ordinary numbers, both directions in the same panel. It's handy for anyone deciphering a copyright date, a chapter or movie credit, a clock face, or a monument inscription, as well as students checking homework and writers who want to format a year or volume number correctly.
Use the mode toggle to pick a direction. In "Number to Roman" type a value and the result appears live; in "Roman to Number" type letters (case doesn't matter, since input is read in uppercase) and you get the integer. Beyond the big result, the Status field tells you whether the entry is valid, out of range, or malformed, and the "Other value" field echoes the matching input so you can confirm both halves of the pair at a glance.
One thing worth knowing: the decoder is strict. It only accepts a numeral that exactly matches the single canonical spelling, so non-standard forms like IIII for 4 or VC for 95 are flagged as "Not a valid numeral" even though a person might guess the intended value. This is deliberate and helps you catch typos, but it means you should write numerals in standard subtractive form (IV, IX, XL, XC, CD, CM).
A practical caveat: there is no Roman symbol for zero and no standard symbol above 3999, so dates like a far-future year or a value of 0 simply won't convert. If you need very large numbers, the historical "vinculum" (a bar over a letter to multiply by 1000) isn't part of this basic system and isn't supported here.
Frequently asked questions
Why can't I convert numbers above 3999?
Standard Roman numerals only go up to 3999 (MMMCMXCIX). Larger numbers historically used a bar over symbols to multiply by 1000, which isn't part of the basic system, so this tool caps the range at 1–3999.
What does a subtractive pair like IV or CM mean?
When a smaller symbol appears before a larger one, you subtract it: IV = 5−1 = 4, IX = 10−1 = 9, and CM = 1000−100 = 900. This keeps numerals compact instead of writing IIII or DCCCC.
Is my data uploaded anywhere?
No — this calculator runs entirely in your browser. Your inputs never leave your device, and it works offline once loaded.
Is this calculator free?
Yes, completely free with no sign-up and no limits.
People also ask
How do you write 2024 in Roman numerals?
2024 is MMXXIV: MM is 2000, XX is 20, and IV is 4. You build it from the largest values down and use the subtractive pair IV for the four.
What are the seven basic Roman numeral symbols and their values?
They are I=1, V=5, X=10, L=50, C=100, D=500, and M=1000. Every standard numeral from 1 to 3999 is spelled using combinations of these seven letters.
Why is IIII sometimes seen on clocks if it isn't standard?
Clockmakers have traditionally used IIII for 4 instead of IV for visual balance and symmetry on the dial. It is a stylistic convention, not the standard subtractive spelling, so strict converters treat IV as the correct form.
Can Roman numerals represent zero or negative numbers?
No. The classical Roman system has no symbol for zero and no notation for negative numbers, which is why converters typically start at 1.
How are years like 1994 written and read in Roman numerals?
1994 is MCMXCIV: M is 1000, CM is 900, XC is 90, and IV is 4. Reading it back, you sum the symbols and subtract whenever a smaller symbol sits before a larger one.
How do you convert a Roman numeral back to a number by hand?
Add each symbol's value going left to right, but subtract a symbol when a smaller one appears immediately before a larger one. For example, in MCMXCIV the C before M counts as minus 100, giving CM = 900.
Is there a Roman numeral for numbers above 3999?
Not in the basic system. Larger values historically used a bar (vinculum) placed over a letter to multiply it by 1000, but that is an extension and is not part of standard 1 to 3999 notation.
What is the largest number you can write with standard Roman numerals?
3999, written MMMCMXCIX, is the largest using only the seven basic symbols without the multiplying bar. Going higher requires the vinculum or other non-standard notations.
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