How Roman numerals work
Roman numerals write numbers with seven letters. Each letter has a fixed value, and there is no place value as in 1,994, where the position of a digit tells you whether it means ones, tens or hundreds. Instead you add the letters up, with one exception for subtraction.
| Letter | I | V | X | L | C | D | M |
|---|---|---|---|---|---|---|---|
| Value | 1 | 5 | 10 | 50 | 100 | 500 | 1,000 |
Letters are written from the largest value to the smallest and added: VIII is 5 + 1 + 1 + 1 = 8, and MDCLX is 1,000 + 500 + 100 + 50 + 10 = 1,660. When a smaller letter stands before a larger one, it is subtracted instead: IV is 5 − 1 = 4 and XC is 100 − 10 = 90.
The rules for valid Roman numerals
Modern standard form follows a few rules, as described for example by the Mathwords reference. The converter checks every numeral you type against them:
- Only six subtractive pairs exist: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900). I goes only before V and X, X only before L and C, and C only before D and M.
- V, L and D are never subtracted and never repeated. VX is not 5, and VV is not 10; you write V and X.
- No letter appears more than three times in a row. 4 is IV, not IIII, and 40 is XL, not XXXX.
- Only one letter is subtracted at a time. 8 is VIII, not IIX, and 99 is XCIX, not IC.
How to convert a number step by step
Split the number into thousands, hundreds, tens and ones, write each part on its own and put them together. The breakdown in the converter shows exactly this. For 1994:
A common slip is to look for the shortest way to subtract. 49 is not IL (50 − 1), because I may only go before V and X. Write 40 and 9 separately: XL + IX = XLIX. In the same way 1999 is MCMXCIX, not MIM, and 990 is CMXC, not XM.
To translate a Roman numeral back into a number, read it from left to right. Add each letter, unless the next letter is larger; then subtract it. MCMXCIV is 1,000 + (1,000 − 100) + (100 − 10) + (5 − 1) = 1,994.
Common mistakes the converter catches
| Written | Problem | Correct |
|---|---|---|
| IIII | I four times in a row | IV (4) |
| VX | V is never subtracted | V (5) |
| IL | I only goes before V and X | XLIX (49) |
| IC | I only goes before V and X | XCIX (99) |
| IIX | Two letters subtracted | VIII (8) |
| MIM | I only goes before V and X | MCMXCIX (1999) |
| VV | V is never repeated | X (10) |
Numbers above 3,999: the vinculum
With at most three M's in a row, standard form ends at MMMCMXCIX, which is 3,999. For larger numbers a horizontal bar over a letter, called a vinculum, multiplies its value by 1,000. Turn on large numbers in the converter to use it. The thousands are written with a bar and the rest without, so 4,500 is IVD.
| Number | Roman numeral |
|---|---|
| 4,000 | IV |
| 5,000 | V |
| 10,000 | X |
| 50,000 | L |
| 100,000 | C |
| 500,000 | D |
| 1,000,000 | M |
When you copy a numeral with a bar, the bar is copied as a combining overline character (U+0305) after each letter.
Dates and years in Roman numerals
For a date, convert the month, the day and the year one by one and keep the separators. In the American order MM.DD.YYYY, July 4, 1776 is VII.IV.MDCCLXXVI. In day-first order it is IV.VII.MDCCLXXVI. Before you use a Roman date for a tattoo, an engraving or an invitation, check that the order matches what the reader expects, since 4.7 reads as April 7 in month-first order and as July 4 in day-first order. Years are simply numbers: the converter writes any year from 1 to 3999.
Years from 1960 to 2035
Roman numerals chart 1 to 100
The numbers from 1 to 100, plus the hundreds and thousands below. Every number follows the same pattern, so once you know 1 to 9 for ones, tens and hundreds, you can write any number up to 3,999.
| Number | Roman numeral | Number | Roman numeral |
|---|---|---|---|
| 200 | CC | 900 | CM |
| 300 | CCC | 1,000 | M |
| 400 | CD | 1,500 | MD |
| 500 | D | 2,000 | MM |
| 600 | DC | 3,000 | MMM |
| 700 | DCC | 3,999 | MMMCMXCIX |
| 800 | DCCC |
The building blocks the converter uses, largest first, are M (1,000), CM (900), D (500), CD (400), C (100), XC (90), L (50), XL (40), X (10), IX (9), V (5), IV (4), I (1).
Where Roman numerals are still used
You still see them on some clock faces, in Super Bowl names and in the copyright year at the end of film credits. Lowercase numerals like i, ii and iii have the same values; switch on lowercase if you need them.
How to use the Roman numeral converter
- 1Type a number to convert it to Roman numerals, or type a Roman numeral to translate it into a number. The other field fills in as you type.
- 2Read the step-by-step breakdown under the result. If a numeral breaks a rule, you see why and can tap the suggested correct form.
- 3For numbers above 3,999 turn on large numbers. For a date, pick it below, choose the order and separator, and copy the result.
Frequently asked questions
How do you write 2026 in Roman numerals?
2026 is MMXXVI. Split the number into thousands, tens and ones: 2,000 is MM, 20 is XX and 6 is VI. Written together that gives MMXXVI. The year 2025 is MMXXV and 2027 is MMXXVII.
Why is 4 written IV and not IIII?
In standard form a letter may not appear more than three times in a row, so 4 is one less than five, IV, and 9 is one less than ten, IX. The converter treats IIII as a mistake and suggests IV.
What is the largest Roman numeral?
With the common rule that no letter repeats more than three times, the largest standard numeral is MMMCMXCIX, which is 3,999. Some guides allow M to repeat more often. For bigger numbers, a bar over a letter multiplies it by 1,000, so the converter can go up to 3,999,999 when you turn on large numbers.
What does a line over a Roman numeral mean?
A horizontal bar over a letter, called a vinculum, multiplies its value by 1,000. V with a bar is 5,000, X with a bar is 10,000 and M with a bar is 1,000,000. To type one here, put an underscore before the letter: _V reads as V with a bar.
How do I write a date in Roman numerals?
Convert the month, the day and the year separately and keep the separators. In the American order MM.DD.YYYY, July 4, 1776 becomes VII.IV.MDCCLXXVI. The date converter above does this for any date from year 1 to 3999 and also writes the day first or the year first.
Why does the converter say my numeral is not valid?
It checks the rules of standard form: only I, X and C are subtracted, and only from the next two larger letters (IV, IX, XL, XC, CD, CM), V, L and D never repeat, and the letters go from the largest value to the smallest. When a numeral breaks a rule, you see which one and the correct way to write the number you probably meant, like XLIX for IL.
Are lowercase Roman numerals the same?
Yes. i, v, x, l, c, d and m have the same values as the capital letters, and the converter reads both. Turn on lowercase if you need numerals like xiv for page numbers or an outline.