Roman Numeral Converter

Convert between Roman numerals and Arabic (decimal) numbers in both directions.

Roman Numeral Converter tool

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Example

Input: 2024 to Roman numerals

Result: MMXXIV

2024 = 2000 + 20 + 4 = MM + XX + IV, using the subtractive pair IV for 4.

Roman Numerals People Look Up

NumberRoman numeral
4IV
9IX
14XIV
19XIX
40XL
49XLIX
90XC
99XCIX
400CD
900CM
1999MCMXCIX
2000MM
2026MMXXVI
3999MMMCMXCIX
  1. Type in either box - the Decimal Number box or the Roman Numeral box - and the other box converts automatically.
  2. For Roman to Arabic, enter a Roman numeral string like XIV or MCMLXXXIV in the Roman Numeral box.
  3. For Arabic to Roman, enter any number between 1 and 3999 in the Decimal Number box.
  4. View the converted result instantly, with an error message and suggested correction for invalid numerals.
  5. Use the values listed in the Formula section to learn Roman numeral symbols.
  6. Click the copy button to copy the converted result.

How to Read and Write Roman Numerals

Roman numerals use seven letters: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1,000. This converter turns a number from 1 to 3,999 into Roman numerals, or a Roman numeral back into a number. For example, 2026 is MMXXVI. Type in either box and the other one updates.

The rules are simple once you see them. Write the largest values first and add them up, so XVI is 10 + 5 + 1 = 16. When a smaller letter comes before a larger one, subtract it instead. Only six such pairs are standard: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). That is why 1999 is MCMXCIX, not MIM.

The converter checks Roman numerals and suggests the standard form when something is off. IIII is flagged with a suggestion of IV. IC is read as 99 and corrected to XCIX. Letters can be typed in lower case. Only the seven Roman letters are accepted. The range stops at 3,999, written MMMCMXCIX. The Romans had no symbol for zero. Bigger numbers used a bar over a letter to multiply it by 1,000, which this tool does not cover.

Roman numerals still appear on clock faces, book chapters, film credits and the names of monarchs. Big sporting events use them too, so Super Bowl LX is the 60th. The Formula section lists every symbol and subtractive pair. For converting between other number systems, such as binary and hex, try the Number Base Converter.

Formula / How It Works

I=1, V=5, X=10, L=50, C=100, D=500, M=1000 | Subtractive pairs: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900

Frequently Asked Questions

There are seven symbols: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1,000. Every other number is built from these. A symbol can repeat up to three times in a row, so 3 is III and 30 is XXX, but 4 is IV rather than IIII.
When a smaller symbol comes right before a larger one, you subtract it. There are six standard pairs: IV = 4, IX = 9, XL = 40, XC = 90, CD = 400 and CM = 900. For example, 1994 is M + CM + XC + IV = MCMXCIV. Only I, X and C are ever subtracted.
With the standard symbols, the largest is 3,999, written MMMCMXCIX. Larger numbers were written with a bar over a letter, which multiplies it by 1,000. That extended form is rare today and this converter does not support it.
No. The Roman system had no symbol for zero, since it was built for counting and recording amounts rather than place-value arithmetic. Medieval writers sometimes used the word nulla, meaning none, where we would write 0.
It is a long clockmaking tradition, and IIII can look more balanced opposite the VIII on the dial. Both forms are understood, but IV is the standard modern form. If you type IIII here, the converter flags it and suggests IV.

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