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Roman Numeral Converter
Convert numbers to Roman numerals and back — with the subtractive breakdown (IV = 4, not IIII), a reference chart, and both directions in your browser. Great for date tattoos and anniversaries: 2024 is MMXXIV. Standard notation covers 1–3999; larger values need a vinculum (noted). Decoding validates the numeral and rejects malformed input. Accurate, instant and free — for United States.
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2024 in Roman numerals
MMXXIV
Breakdown: MM = 2000, XX = 20, IV = 4
Reference chart
Base symbols
- I1
- V5
- X10
- L50
- C100
- D500
- M1,000
Subtractive pairs
- IV4
- IX9
- XL40
- XC90
- CD400
- CM900
1 to 10
- 1I
- 2II
- 3III
- 4IV
- 5V
- 6VI
- 7VII
- 8VIII
- 9IX
- 10X
The range is 1–3999, and IV is not IIII
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed July 2026. Figures follow the methods and sources set out in our editorial standards.
Conversions use standard subtractive Roman notation (IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900) over the range 1–3999. Decoding validates the numeral canonically and rejects malformed input such as IIII or VX. Clock-face IIII and vinculum (overline) notation for values above 3999 are noted but not generated.
Wikipedia · Roman numerals
Converting other things? Switch between metric and imperial with the Unit Converter, or count the days between two dates with the Date Difference Calculator.
Seven symbols, built by place value
Roman numerals spell every number from 1 to 3999 out of just seven letters — I (1), V (5), X (10), L (50), C (100), D (500) and M (1000). A number is built one place value at a time — thousands, then hundreds, then tens, then units — and the groups are written side by side. There is no symbol for zero.
The seven letters
Fixed values
- I = 1, V = 5, X = 10
- L = 50, C = 100
- D = 500, M = 1000
Place value
Greedy, largest first
- Thousands → hundreds → tens → units
- Each place is its own group
- Repeat a symbol at most 3×
Two directions
Encode & decode
- Number → numeral (e.g. 2024 → MMXXIV)
- Numeral → number (e.g. IX → 9)
- Decode validates the spelling
Why 4 is IV, not IIII
Standard notation never repeats I, X, C or M four times in a row. When a fourth would be needed, you subtract instead: a smaller symbol placed before a larger one means "that much less". So 4 is IV (5 − 1) and 9 is IX (10 − 1).
The six valid pairs
Nothing else subtracts
- IV = 4, IX = 9
- XL = 40, XC = 90
- CD = 400, CM = 900
One step down only
Why 99 is XCIX
- Subtract only I from V/X, X from L/C, C from D/M
- 99 = XC + IX = XCIX
- Never IC, IL or IIX
IIII on clocks is the exception, not the rule
Reading a year, the 1–3999 range, and decoding
The everyday use of Roman numerals is years — on buildings, movie credits, copyright lines and date tattoos. To read one, split it into place-value groups and add: MMXXIV = MM (2000) + XX (20) + IV (4) = 2024. To decode any numeral, add each symbol and subtract any that sits before a larger one.
Common years
Tattoo & date intent
- 2000 = MM
- 2024 = MMXXIV
- 1999 = MCMXCIX
The range
1–3999, then a vinculum
- Smallest: 1 = I
- Largest: 3999 = MMMCMXCIX
- Above 3999 needs an overline (vinculum)
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Why we stop at 3999
Frequently asked questions
4 is written IV, not IIII. Roman numerals avoid repeating a symbol four times by using a subtractive pair: placing the smaller I before the larger V means "one less than five", so IV = 5 − 1 = 4. The same rule gives IX = 9 (10 − 1). You will occasionally see IIII on clock faces for visual balance, but IV is the standard mathematical form and the one this converter produces.
Standard Roman numerals never repeat I, X, C or M more than three times in a row. When a fourth would be needed, you subtract instead: 4 becomes IV (5 − 1) and 40 becomes XL (50 − 10). Only six subtractive pairs are valid — IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900) — and a smaller symbol can only be subtracted from the next one or two sizes up (so 99 is XCIX, never IC). This keeps every number a single, unambiguous spelling.
Break it into place-value groups and add them up. MMXXIV splits into MM (1000 + 1000 = 2000), XX (10 + 10 = 20) and IV (4), which total 2024. Reading left to right, symbols normally add; whenever a smaller symbol sits before a larger one it subtracts (the IV in MMXXIV). Years are the most common everyday use of Roman numerals — dates on buildings, movie credits, Super Bowls, copyright lines and date tattoos.
In standard notation the range is 1 to 3999 (MMMCMXCIX), and there is no symbol for zero. 3999 is the ceiling because M can repeat at most three times, capping the thousands at 3000 + 900 + 90 + 9. To go higher, scribes used a vinculum — an overline that multiplies a numeral by 1000, so an overlined V means 5000 — but the vinculum has no single agreed digital representation, so this converter deliberately stays within the well-defined 1–3999 range and flags anything outside it.
Add each symbol’s value from left to right, subtracting any symbol that appears immediately before a larger one. Using I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000: MCMXCIX is M (1000) + CM (900) + XC (90) + IX (9) = 1999. This converter does it for you and also validates the input — it rejects malformed numerals such as IIII, VX or IC and tells you when a string is not a legal numeral.
No. Both directions — number to numeral and numeral to number — run entirely in your browser with a small deterministic algorithm, nothing is uploaded, logged or stored, and it works offline once the page has loaded. There is no lookup table fetched from anywhere; the numeral is generated on the spot from the standard subtractive rules.
References
Method: numbers are converted greedily, largest symbol first, using the standard subtractive pairs (IV, IX, XL, XC, CD, CM), so 4 is IV (never IIII) and the range is 1–3999. Decoding adds each symbol's value, subtracting any symbol that precedes a larger one, and rejects non-canonical spellings such as IIII, VX or IC. Everything runs in your browser — no data is sent to a server.
How we calculate this
Reviewed by Reckonist Editorial · Last reviewed 5 July 2026. Figures follow the methods and sources set out in our editorial standards.
This tool converts between numbers and Roman numerals in your browser using standard subtractive notation (IV not IIII), covering the range 1–3999. Values above 3999 need a vinculum (overline) and are out of scope; the tool flags them rather than guessing.
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