Roman Numeral Converter
Convert numbers to Roman numerals and Roman numerals to numbers.
Works both ways for 1 to 3999, with strict validation, live as you type.
Your Roman Numeral
How does a Roman numeral converter work?
A Roman numeral converter translates between the numbers we write today and the Roman system of letters. This one works both ways: type a number to get its Roman numeral, or type a numeral to get the number. Pick a direction, enter your value, and the result appears instantly, ready to copy. It runs entirely in your browser, so nothing you type leaves your device.
Roman numerals use seven symbols: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1000. You read them left to right and add the values, with one twist called subtractive notation: when a smaller symbol sits before a larger one, you subtract it. That is why 4 is IV (one less than five) rather than IIII, and why 9 is IX, 40 is XL, 90 is XC, 400 is CD and 900 is CM. The tool always produces this standard form.
Standard Roman numerals cover 1 to 3999. There is no symbol for zero, because the system was built for counting rather than place-value arithmetic, and there is no agreed standard form above 3999, since you do not write more than three M in a row. Bigger numbers were sometimes shown with a bar over a symbol to multiply it by a thousand, but that notation is not standardised, so this converter stops at 3999 instead of guessing. Enter a value outside the range and the tool says so rather than returning something misleading.
Roman numerals still turn up in plenty of places: years on buildings, films and copyright lines, names of monarchs and popes like Henry VIII, clock faces, book outlines and chapter numbers. When you decode a numeral, the tool checks it is well formed first: it works out the value, converts that value back to a numeral, and accepts your input only if the two match, so malformed forms like IIII or VV are rejected. This sits beside the other number tools: the number to words converter spells a number out in English, and the word counter counts your writing. Everything runs in your browser with no account and nothing to install. Enter a number or a numeral above to convert it instantly.
The Seven Roman Numeral Symbols
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1000 |
Roman Numeral Converter Examples
| Direction | Input | Result |
|---|---|---|
| Number to Roman | 4 | IV |
| Number to Roman | 9 | IX |
| Number to Roman | 14 | XIV |
| Number to Roman | 40 | XL |
| Number to Roman | 90 | XC |
| Number to Roman | 2024 | MMXXIV |
| Number to Roman | 3999 | MMMCMXCIX |
| Roman to Number | MCMLXXXIV | 1984 |
*Every row is produced by the same engine this page uses. The input column is the real value; the result column is what the tool returns.
Features of Our Roman Numeral Converter
Ways
1 to 3999
Validation
Dates
You Type
Copy
& Private
Frequently Asked Questions
Click any question to read the answer.
How do you read Roman numerals?
Read the symbols from left to right and add their values, with one exception: when a smaller symbol comes before a larger one, you subtract it. So VI is 5 plus 1, which is 6, but IV is 5 minus 1, which is 4. The seven symbols are I (1), V (5), X (10), L (50), C (100), D (500) and M (1000). Larger symbols come first, then the smaller ones, so MMXXIV reads as 1000 plus 1000 plus 10 plus 10 plus 4, which is 2024.
What is the largest Roman numeral?
In standard notation the largest value is 3999, written MMMCMXCIX. The system only has symbols up to M (1000), and you do not write more than three M in a row, so 3999 is the ceiling. Larger numbers were sometimes shown with a bar over a symbol to multiply it by 1000, but that vinculum notation is not standardised, so this tool stops at 3999 rather than guess.
Is there a Roman numeral for zero?
No. Roman numerals have no symbol for zero, because the system was built for counting and recording amounts, where zero was simply written as a word or left out. The idea of zero as a number reached Europe much later through the Hindu-Arabic system we use today. That is why this converter starts at 1, the smallest value Roman numerals can represent.
Why is 4 written IV and not IIII?
Standard Roman notation uses subtraction to keep numerals short, so 4 is one less than 5, written IV, rather than four ones, IIII. The same rule gives IX for 9, XL for 40, XC for 90, CD for 400 and CM for 900. You may still see IIII on some clock faces, a traditional style choice, but the standard, validated form is IV, which is what this tool accepts and produces.
How do I write a year in Roman numerals?
Break the year into thousands, hundreds, tens and units and write each part, largest first. For 2024 that is MM for 2000, XX for 20 and IV for 4, giving MMXXIV. For 1984 it is M, CM, LXXX and IV, which is MCMLXXXIV. Type the year into the Number to Roman side of this tool and it does the breakdown for you.
What does a given Roman numeral mean?
Use the Roman to Number side of the tool: type the numeral and it returns the integer, after checking that the numeral is well formed. For example XLII is 42 and MCMXCIX is 1999. If the numeral is not valid, such as IIII or VV, the tool tells you instead of returning a misleading number.
Why does the tool reject some numerals?
It validates strictly, so it only accepts the one canonical spelling of each value. It works out the value of what you typed, converts that value back to a numeral, and accepts your input only if the two match exactly. That single check rejects malformed forms like IIII (the standard form is IV), VV (which should be X) and IC (which should be XCIX), so you can trust any numeral it accepts.
Is my input stored when I use this tool?
No. The converter runs entirely as JavaScript inside your browser, so what you type is never uploaded, logged, or sent to a server. The page keeps working offline once it has loaded, and nothing leaves your device. You can convert a date or a number with no privacy risk at all.