Roman Numeral Converter

How Roman numerals work

Roman numerals use seven symbols: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. When a smaller value precedes a larger one, it is subtracted: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900. The system handles numbers from 1 to 3999 without a symbol for zero.

How do I convert numbers to Roman numerals?

To convert a number to Roman numerals, repeatedly subtract the largest possible symbol value and append its symbol, using six subtractive pairs, like IV for 4, to avoid four repeated symbols in a row. Example: 2024 converts to MMXXIV (1000+1000+10+10+4).

Steps to convert a number to Roman numerals

1. Start with the largest value symbol (M = 1000) and subtract it from the number as many times as possible, appending an M each time.
2. Move to the next value, checking the subtractive pairs first (CM=900, CD=400, XC=90, XL=40, IX=9, IV=4) before the plain symbols (D=500, C=100, L=50, X=10, V=5, I=1).
3. Subtract each matched value from the remaining number and append its symbol, repeating until that value no longer fits.
4. Continue through all thirteen values, from 1000 down to 1, until the remaining number reaches 0.
5. To convert Roman numerals back to a number, add each symbol's value, but subtract it instead if a smaller-value symbol comes right before a larger one.

Roman numeral symbols

• A smaller symbol before a larger one means subtraction (IV = 5 - 1 = 4)
• A symbol repeated up to three times means addition (III = 1+1+1 = 3); no symbol repeats more than three times

Common Roman numeral values

What is IV in Roman numerals?

IV is 4. It's the subtractive form of V (5) minus I (1).

What is IX in Roman numerals?

IX is 9. It's the subtractive form of X (10) minus I (1).

What is XIV in Roman numerals?

XIV is 14: X (10) + IV (4).

What is XIX in Roman numerals?

XIX is 19: X (10) + IX (9).

What is XL in Roman numerals?

XL is 40. It's the subtractive form of L (50) minus X (10).

What is XLIX in Roman numerals?

XLIX is 49: XL (40) + IX (9).

What is XC in Roman numerals?

XC is 90. It's the subtractive form of C (100) minus X (10).

What is XCIX in Roman numerals?

XCIX is 99: XC (90) + IX (9).

What is CD in Roman numerals?

CD is 400. It's the subtractive form of D (500) minus C (100).

What is CM in Roman numerals?

CM is 900. It's the subtractive form of M (1000) minus C (100).

What is MMXXV in Roman numerals?

MMXXV is 2025: M+M+X+X+V = 1000+1000+10+10+5.

What is MMXXVI in Roman numerals?

MMXXVI is 2026: M+M+X+X+V+I = 1000+1000+10+10+5+1.

Example Arabic-to-Roman conversions

Roman numerals 1 to 100

Frequently asked questions

What is the largest number Roman numerals can represent?

Using the standard symbols without extra marks, Roman numerals represent numbers from 1 to 3999 (MMMCMXCIX). Larger numbers traditionally use a bar over a symbol to multiply its value by 1,000, which this tool does not support.

Is there a symbol for zero in Roman numerals?

No. The Roman numeral system has no symbol for zero; it was designed for counting and accounting, where a quantity of nothing simply was not written down. The concept of zero as a number came from separate mathematical traditions.

Why is 4 written as IV instead of IIII?

IIII, four I's in a row, does appear historically, especially on clock faces, but the standard modern convention uses the subtractive form IV to avoid repeating any symbol more than three times, which is why 1994 is MCMXCIV rather than a longer repetitive string.

How do I read a Roman numeral like MCMXCIV?

Break it into subtractive pairs and symbols from left to right: M (1000) + CM (900) + XC (90) + IV (4) = 1994. Reading left to right and adding each recognized chunk gives the total.

This tool converts whole numbers from 1 to 3999 using the standard modern subtractive notation; it does not support zero, negative numbers, fractions, or the vinculum (overline) notation used historically for numbers above 3999.

Sources: Florian Cajori, A History of Mathematical Notations (Roman numeral subtractive convention)

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Last updated: 2026-08-24