Skip to main content

Roman Arabic Numerals: Online Converter

The Output will appear here...
  • I
    1
  • V
    5
  • X
    10
  • L
    50
  • C
    100
  • D
    500
  • M
    1000

You can enter a mix of Roman and Arabic numerals, separated by spaces or new lines, into the input area. As you type, the converter instantly identifies and converts valid Arabic and Roman numerals to their respective counterparts.

The converted results are neatly presented in a table format with two columns, making it easy to compare the original input with the converted output. You can quickly identify the Roman and Arabic equivalents of the numerals you've entered.

For Arabic to Roman number conversion, our tool accepts numbers within the range of 1 to 3999, inclusive.

Master Roman Numerals with our interactive worksheet! Practice conversions, comparisons, and calculations at your own pace.

Roman Numerals Cheat Sheet

The Roman numeral symbols and their values are:

  • I
    1
  • V
    5
  • X
    10
  • L
    50
  • C
    100
  • D
    500
  • M
    1000
1

Addition & Repetition

When a symbol appears after a larger symbol, it is added to the larger symbol's value.

XV = 10 + 5 = 15

LIII = 50 + 3 = 53

If a symbol is repeated, the values are added together.

XXX = 10 + 10 + 10 = 30

CC = 100 + 100 = 200

2

Repetition Rules

The symbols I, X, C, and M can be repeated, but not more than three times in a row.

I, II, III, X, XX, XXX, C, CC, CCC, M, MM, MMM

IIII, CCCCC, MMMMM

The symbols V, L, and D are never repeated.

VV, LLL, DD

3

Subtraction

When a symbol appears before a larger symbol, it is subtracted from the larger symbol's value.

IV = 5 - 1 = 4

IX = 10 - 1 = 9

XL = 50 - 10 = 40

Then, why is 99 written as XCIX instead of IC? See next card.

IL ≠ 50 - 1 = 49

IC ≠ 100 - 1 = 99

IM ≠ 1000 - 1 = 999

4

Subtractive Combinations

The symbols I, X, and C can be used subtractively only in specific combinations:

This is why:

I can precede V and X.

49 = XLIX, not IL.

X can precede L and C.

99 = XCIX, not IC.

C can precede D and M.

999 = CMXCIX, not IM.

Download this cheat sheet!!