Roman Numeral Converter
This Roman numeral converter translates between ordinary numbers and Roman numerals in both directions, using the standard subtractive notation where IV is 4 and IX is 9 rather than IIII and VIIII. Reading is more forgiving than writing: a non-standard but unambiguous form such as IIII is accepted and its value returned, with a note giving the standard spelling. The system has real limits, and they are reported rather than fudged — there is no zero, no negative numbers, and no agreed plain-text way to write values above 3,999, which need an overline to multiply a numeral by a thousand.
How it works
Converts between ordinary numbers and Roman numerals in both directions, following the standard subtractive notation where IV is 4 and IX is 9.
The system has no zero, no negative numbers and no agreed plain-text way to write values above 3,999 — that needs an overline to multiply by a thousand. Those limits are reported rather than fudged.
Everything runs in your browser — nothing you enter is sent to a server.
The seven symbols
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1,000 |
Subtractive notation
A smaller numeral placed before a larger one is subtracted from it. Only six such pairs are standard:
IV (4), IX (9), XL (40), XC (90), CD (400) and
CM (900). Anything else — IL for 49, say — is not standard, however logical it looks.
Why IIII appears on clocks
Clock faces traditionally use IIII rather than IV. The usual explanation is visual
balance: IIII sits opposite VIII and makes the dial look symmetrical. Both readings are
accepted here.
Frequently asked questions
How do I convert a number to Roman numerals?
Type the number with the direction set to Number → Roman. The numeral appears immediately.
Why is 4 written IV and not IIII?
Subtractive notation: a smaller numeral before a larger one is subtracted. It keeps numerals short and is the standard form, though IIII does appear on clock faces by convention.
Will it read a non-standard numeral?
Yes. IIII is accepted and returns 4, with a note giving the standard spelling. Reading is deliberately more permissive than writing.
Why is there no zero?
The system has no symbol for zero and no concept of one — it was built for counting and recording quantities, not for arithmetic.
What is the largest number?
3,999, written MMMCMXCIX. Above that you need an overline over a numeral to multiply it by a thousand, and there is no agreed way to write that in plain text.
Is anything uploaded?
No. The conversion runs entirely in your browser.
Related tools
Number to Words Converter
This number to words converter spells out figures for cheques, contracts and invoices.
Number Base Converter
A number base converter for binary, hex, decimal, octal, Roman numerals, balanced ternary, negabinary and more.
Number Sorter
This number sorter orders numbers properly, and gives you the sum, mean and median.