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Roman Numeral Converter

Convert between numbers and Roman numerals (1-3999)

Number to Roman

MMXXIV

Roman to Number

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Reference Chart

RomanValueRomanValue
I1V5
X10L50
C100D500
M1000IV4
IX9XL40
XC90CD400
CM900

Roman Numeral Rules

Roman numerals use seven symbols: I, V, X, L, C, D, M. When a smaller numeral appears before a larger one, it's subtracted (IV=4). When it appears after, it's added (VI=6). A numeral can be repeated up to 3 times (III=3, but 4=IV).

Roman numerals, in full

Roman numerals use seven letters — I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000 — and the largest number the standard system can write is 3,999 (MMMCMXCIX). Everything else is built by adding those letters left to right, with six subtractive pairs (IV, IX, XL, XC, CD, CM) as the only exceptions.

The seven symbols and the six subtractive pairs

NumeralValueNumeralValue
I1IV4
V5IX9
X10XL40
L50XC90
C100CD400
D500CM900
M1000——

The four rules that decide every conversion

  1. Write the largest value you can, then repeat down the list. 2026 = MM + XX + VI = MMXXVI.
  2. A letter may repeat at most three times in a row. 3 is III, but 4 is not IIII — it is IV.
  3. Only I, X and C are ever subtracted, and only from the next two larger symbols. That gives exactly six legal pairs: IV, IX, XL, XC, CD, CM. VL, IC and IL are not valid.
  4. V, L and D are never repeated and never subtracted — there is no VV (that is X) and no VX.

Common numbers at a glance

NumberRomanNumberRomanNumberRoman
1I14XIV100C
2II19XIX400CD
3III20XX500D
4IV40XL900CM
5V50L1000M
9IX90XC2026MMXXVI
10X99XCIX3999MMMCMXCIX

Worked example — writing 1,984

Convert 1984 to Roman numerals

1984 − 1000 = 984 → M

984 − 900 = 84 → CM (900 is CM, not DCCCC)

84 − 50 = 34 → L

34 − 10 − 10 − 10 = 4 → XXX

4 → IV

1984 = MCMLXXXIV

Why clock faces show IIII

Many analogue clocks and church dials print IIII for four instead of IV. It is not an error in the numbering system — it is a design convention. IIII balances the VIII opposite it visually, and it lets a clockmaker cut the dial from a run of exactly twenty I’s, four V’s and four X’s. Big Ben is the famous exception that uses IV.

More questions people ask

How do you write 2026 in Roman numerals?

2026 is MMXXVI — MM for 2000, XX for 20 and VI for 6.

Is there a Roman numeral for zero?

No. The Roman system has no symbol for zero and no concept of place value. Medieval scribes writing in Latin used the word nulla for nothing when they needed it.

How are numbers above 3,999 written?

With vinculum notation: a bar over a letter multiplies it by 1,000, so a barred V is 5,000 and a barred X is 10,000. Unicode also has dedicated characters, but the plain seven-letter system stops at 3,999.

Can Roman numerals show fractions?

The Romans used a base-12 fraction system with its own marks — S for one half (semis) and dots for twelfths — but these are not part of the modern numeral set and no converter outputs them.

Why is 49 XLIX and not IL?

Subtraction is only allowed from the next two larger symbols, so I can only sit before V or X. 49 has to be built as 40 + 9 = XL + IX = XLIX.

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Frequently Asked Questions

What are the basic Roman numerals?
I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Subtractive: IV=4, IX=9, XL=40, XC=90, CD=400, CM=900.
What is the largest Roman numeral?
Standard system: 3999 (MMMCMXCIX). Vinculum notation extends beyond by placing a bar over letters.
Why is 4 written as IV?
Subtractive notation: IV means 5-1=4. It's more compact than IIII (though IIII appears on some clock faces).

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