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§ · free tool

Roman numeral converter. Both directions, instantly.

Type a whole number to see its Roman numeral, or paste a numeral to get the value back. Handles 1 to 3,999,999 with overline notation, all in your browser, nothing uploaded.

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A free online tool by Digital Heroes

Enter a whole number from 1 to 3,999,999.

Result appears here

Letters I V X L C D M. For overline (thousands) values, wrap the group in parentheses, e.g. (V) for 5,000.

Result appears here

The seven symbols

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

Subtractive pairs (IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900) keep numerals short. Standard numerals only reach 3,999 (MMMCMXCIX). For larger values, Roman scribes drew an overline (vinculum) over a numeral to multiply it by 1,000: an overlined V is 5,000 and an overlined X is 10,000. This tool draws the overline above the result, and accepts (V) parenthesis notation when you type, since overlines are hard to enter on a keyboard.

§ 02 · what you can do

Everything the converter handles.

  • Convert any number to Roman numerals, type a whole number and the numeral appears live as you type.
  • Decode Roman numerals back to a number, paste any numeral and get the integer value, formatted with thousands separators.
  • Work up to 3,999,999 using overline (vinculum) notation, drawn visually above the thousands group.
  • Type overline values with parentheses, enter (V) for 5,000 or (X)CMXCIX for 10,999, no special characters needed.
  • Get strict validation, malformed numerals like IIII, VX or IL are rejected with a clear message, not silently misread.
  • Copy either result to your clipboard with one click.
§ 03 · how to use it

Four steps, no manual.

  1. To convert a number to Roman numerals, type a whole number (1 to 3,999,999) into the top field, the result appears instantly below it.
  2. To convert Roman numerals to a number, type or paste the numeral (for example MMXXVI) into the second field.
  3. For values above 3,999, use parenthesis notation for the overline group, such as (V)CMXCIX for 5,999.
  4. Click Copy next to either result to send it to your clipboard.
§ 04 · faq

Frequently asked questions.

Is the Roman Numeral Converter free?
Yes, completely free for everyone. No sign-up, no account and no usage limits.
Is it private? Is my data uploaded anywhere?
No upload, ever. The converter runs entirely in your browser on your own device, so whatever you type never leaves your computer.
What is the largest number it supports?
3,999,999. Standard numerals stop at 3,999 (MMMCMXCIX); above that this tool uses overline (vinculum) notation, drawing a line over the thousands group to multiply it by 1,000.
How do I type an overline on a keyboard?
You don't need special characters. Wrap the thousands group in parentheses, the tool treats it as overlined and multiplies it by 1,000. For example, type (V)CMXCIX to enter 5,999.
Is there a Roman numeral for zero?
No, the Roman system has no symbol for zero, so numerals begin at 1 (I). Entering 0 or a negative number returns a short explanation rather than a result.
Why does IIII or VX get rejected?
Because they aren't standard form. The decoder validates each numeral by converting it back and checking it matches, so it accepts IV for 4 and IX for 9, but rejects non-standard spellings like IIII, VX or IL.

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