Type a number from 1 to 3999 or a Roman numeral, and the converter gives the other form as you type. Roman numerals use seven letters: I is 1, V 5, X 10, L 50, C 100, D 500 and M 1000. Letters add up, but a smaller one placed before a larger one is subtracted, so IV is 4.
- 20001000 + 1000MM
- 2010 + 10XX
- 45 − 1IV
How to use the converter
- Type a number from 1 to 3999, such as 2024, or a Roman numeral such as XIV. There is one box for both; the converter tells them apart as you type.
- Read the answer under the grid. Each place value is drawn from its own cells, and the orange plane marks the part you are looking at. Point at a row in the breakdown to light up its cells.
- Check the breakdown rows: every row shows the value, how its symbols add or subtract, and the letters it becomes.
- Copy the result with the Copy button or the Enter key. Use the swap button (Alt+S) to turn the answer back into the input and convert the other way.
- Need something unusual? Switch on lowercase, the single Unicode characters (Ⅻ), or the vinculum, a bar over a letter that multiplies it by 1000, for numbers up to 3,999,999.
Roman numerals in one minute
Seven letters do all the work. Each has a fixed value, and a numeral is read from left to right.
- I =1
- V =5
- X =10
- L =50
- C =100
- D =500
- M =1,000
When the values go down, you add them: VIII is 5 + 1 + 1 + 1 = 8. When a smaller symbol stands right before a larger one, you subtract it: IV is 5 − 1 = 4, and XC is 100 − 10 = 90. Only six such pairs are allowed: IV, IX, XL, XC, CD and CM. The same symbol may appear at most three times in a row, and V, L and D are never repeated.
That is why 4 is IV rather than IIII, and why a number is always written place by place: 1994 is M + CM + XC + IV = MCMXCIV. The full set of rules, with history and the clock-face exception, is on the Roman numeral rules page, and every number from 1 to 1000 is in the Roman numerals chart.
Mistakes it catches
Instead of silently “fixing” a wrong numeral, the converter shows what is wrong: the letters that break a rule are drawn as empty, struck cells, and the correct construction is built beside them. A few forms people type:
| Typed | What is wrong | Suggested |
|---|---|---|
| IIII | I can appear at most three times in a row. | IV (4) |
| VIIII | Four Is after a five is an old additive form; the standard form uses subtraction. | IX (9) |
| IC | I cannot be subtracted from the next letter. | XCIX (99) |
| IIV | Only one I can be subtracted from a larger letter. | IV (4) |
| VX | V cannot be subtracted from the next letter. | V (5) |
| X1X | The digit 1 was typed instead of the letter I. | XIX (19) |
Some of these are not modern errors so much as older habits: IIII survives on clock faces, and VIIII appears in Roman inscriptions. The converter marks them as non-standard and still shows the standard form.
Popular numbers
Each of these has its own page with a breakdown, what is particular about the numeral, and where it turns up, from Super Bowls to kings and film titles.
Popular numerals
Starting from the letters instead: the numerals people look up most, each with how to read it, how to type it and where it appears.
Questions people ask
How do you convert numbers to Roman numerals?
Split the number into thousands, hundreds, tens and ones, write each part with its own symbols, and join them from largest to smallest. For 2024 that is 2000 = MM, 20 = XX and 4 = IV, so 2024 = MMXXIV.
Is 4 IIII or IV?
The standard form is IV: one before five, subtracted. IIII is an older additive spelling that many clock faces still use, but it breaks the rule that a symbol repeats at most three times.
What is 1–10 in Roman numerals?
1 = I, 2 = II, 3 = III, 4 = IV, 5 = V, 6 = VI, 7 = VII, 8 = VIII, 9 = IX, 10 = X.
What is the Roman numeral for 1000?
M is 1000. Three M’s make 3000 (MMM), and 3999 (MMMCMXCIX) is the largest number standard Roman numerals can write; above that a bar over a letter multiplies it by 1000.
How is 99 written in Roman numerals?
99 is XCIX: 90 is XC and 9 is IX. IC looks shorter, but I may only be subtracted from V and X, so the converter flags IC and suggests XCIX.
Is there a Roman numeral for zero?
No. Roman numerals start at I. Where a zero was needed, medieval writers used the Latin word nulla, meaning none.