Roman Numeral Converter

Convert between Roman numerals and Arabic numbers instantly. Free online Roman numeral converter.

Convert Roman numerals to numbers and numbers to Roman numerals. Supports values from 1 to 3,999,999.

Convert Roman / Arabic

Supports numbers 1-3,999,999. Use underscore for overline (e.g., _X = 10,000)

Try:

Reference Chart

Basic Symbols (1-1000)

Vinculum/Overline (x1000)

Using Vinculum (Overline)

For numbers larger than 3,999, Romans used a vinculum (overline) to multiply by 1,000.

Input format: Use underscore before a letter to indicate an overline.

_X = X with overline = 10,000
_XMCMLIV = 11,954
help_outlineHow to Useexpand_more
  1. Enter an Arabic number (1-3,999,999) to convert to Roman numerals
  2. Or enter a Roman numeral to convert to an Arabic number
  3. Click "Convert" to see the result
  4. View the breakdown showing how the conversion works

For numbers greater than 3,999:

Use an underscore (_) before a letter to represent an overline, which multiplies the value by 1,000. For example: _X = 10,000, _C = 100,000, _M = 1,000,000.

infoWhat is Roman Numeral Converter?expand_more

Roman numerals are a number system developed in ancient Rome where letters represent numbers. The modern use of Roman numerals involves the letters I, V, X, L, C, D, and M.

This converter handles numbers from 1 to 3,999,999. For numbers greater than 3,999, a line (overline) over a Roman numeral means it is multiplied by 1,000.

Examples with Overlines:

  • V̅ = 5,000 — Enter as _V
  • X̅ = 10,000 — Enter as _X
  • L̅ = 50,000 — Enter as _L
  • C̅ = 100,000 — Enter as _C
  • C̅M̅ = 900,000 — Enter as _C_M
functionsFormulaexpand_more

Standard Roman Numerals (1-3,999):

I = 1
V = 5
X = 10
L = 50
C = 100
D = 500
M = 1,000

With Overline (×1,000):

I̅ = 1,000
V̅ = 5,000
X̅ = 10,000
L̅ = 50,000
C̅ = 100,000
D̅ = 500,000
M̅ = 1,000,000

Subtractive Notation:

IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900

lightbulbExamplesexpand_more

Standard

2024 = MMXXIV

Standard

1999 = MCMXCIX

Standard

3999 = MMMCMXCIX

With overline

50,000 = L̅

With overline

100,000 = C̅

With overline

1,000,000 = M̅

quizFAQexpand_more
What is the largest number in Roman numerals?expand_more
Using standard notation, the largest number is 3,999 (MMMCMXCIX). With overlines (multiplying by 1,000), this converter supports up to 3,999,999. Historically, various notations were used for larger numbers.
How do I enter overlines for large numbers?expand_more
Use an underscore (_) before the letter. For example, _X means X̅ (10,000), _C means C̅ (100,000), and _M means M̅ (1,000,000). For 900,000, enter _C_M.
What is subtractive notation?expand_more
Subtractive notation places a smaller value before a larger one to indicate subtraction. For example, IV = 5-1 = 4, IX = 10-1 = 9, XL = 50-10 = 40, XC = 100-10 = 90, CD = 500-100 = 400, CM = 1000-100 = 900.
Why is there no zero in Roman numerals?expand_more
The Roman numeral system was developed for counting and practical purposes where zero wasn't needed. The concept of zero as a number came later from Indian and Arabic mathematicians.
Are Roman numerals still used today?expand_more
Yes! Roman numerals appear on clock faces, in movie titles (sequels), book chapters, Super Bowl numbers, building cornerstones, formal outlines, and copyright dates.