Roman Numeral Converter
Choose a mode below and press Calculate for an instant result.
Standard modern converter supports whole numbers from 1 to 3,999.
Convert numbers to Roman numerals or Roman numerals back to numbers, check whether a numeral uses standard modern notation, and see each conversion step.
Choose a mode below and press Calculate for an instant result.
Roman numerals are a number-writing system built from letters. The seven basic symbols are I (1), V (5), X (10), L (50), C (100), D (500), and M (1,000).
Every standard Roman numeral from 1 to 3,999 is built from these seven letters, combined through addition and a small set of subtractive pairs.
| Symbol | Value |
|---|---|
| I | 1 |
| V | 5 |
| X | 10 |
| L | 50 |
| C | 100 |
| D | 500 |
| M | 1,000 |
Roman numerals are still used today for things such as clock faces, book chapters, monarchs and popes, movie sequels, events, copyright dates, and decorative dates.
The common modern system uses both addition and subtraction. For example, VIII is 5 + 1 + 1 + 1, which equals 8. But IV places I before V, so instead of adding, the I is subtracted: 5 minus 1 equals 4.
A smaller symbol placed before a larger one is subtracted instead of added. VI adds; IV subtracts.
| Numeral | Reading | Value |
|---|---|---|
| VI | 5 + 1 | 6 |
| IV | 5 minus 1 | 4 |
The common modern pairs are IV (4), IX (9), XL (40), XC (90), CD (400), and CM (900). Not every smaller numeral can simply be placed before any larger numeral, and that is one of the most important Roman numeral rules.
These are the only subtractive pairs used in standard modern notation.
| Pair | Value |
|---|---|
| IV | 4 |
| IX | 9 |
| XL | 40 |
| XC | 90 |
| CD | 400 |
| CM | 900 |
Only I, X, and C are used subtractively in the common standard modern rules. I may appear before V or X. X may appear before L or C. C may appear before D or M. This calculator does not accept IL, IC, XD, XM, VX, LC, or DM as standard canonical forms, even though a simple left-to-right subtraction could produce a number from them.
You might be tempted to write IC because 100 minus 1 equals 99. But IC is not the standard modern notation, because I is not permitted to subtract from C directly. Ninety is XC. Nine is IX. So 99 is XCIX. This calculator rejects IC as a canonical modern form and suggests XCIX.
IC looks like it could mean 99, but the standard modern form is XCIX.
Break the number into standard Roman-value pieces from largest to smallest. For 1,994, that breakdown is 1,000 + 900 + 90 + 4. Converting each piece gives 1,000 = M, 900 = CM, 90 = XC, and 4 = IV. Combined, that is MCMXCIV.
Each place value converts to its own symbol or pair, and the symbols are joined in order to form the final numeral.
| Value | Symbol |
|---|---|
| 1,000 | M |
| 900 | CM |
| 90 | XC |
| 4 | IV |
Read the numeral using the standard symbol values and valid subtractive pairs. For MCMXCIV, that is M (1,000), CM (900), XC (90), and IV (4), for a total of 1,994. This calculator also validates whether the entered sequence is standard modern notation rather than merely producing arithmetic from any random letter order.
The questions below cover the Roman numerals people look up most often. Each one is read the same way: add symbol values left to right, and subtract only when a smaller value directly precedes a larger one in a standard pair.
IV means 4. The I before V signals subtraction: 5 minus 1 equals 4.
IX means 9. 10 minus 1 equals 9.
XIV means 14. X is 10 and IV is 4, so 10 + 4 = 14.
XIX means 19. X is 10 and IX is 9, so 10 + 9 = 19.
XL means 40. L is 50, and X before it subtracts 10, so 50 minus 10 equals 40.
XLIV means 44. XL is 40 and IV is 4, so 40 + 4 = 44.
XC means 90. 100 minus 10 equals 90.
XCIX means 99. XC is 90 and IX is 9, so 90 + 9 = 99.
CD means 400. 500 minus 100 equals 400.
CM means 900. 1,000 minus 100 equals 900.
Under common modern conventions, I, X, C, and M can repeat up to three times in a row where appropriate. III = 3, XXX = 30, CCC = 300, and MMM = 3,000. V, L, and D are not normally repeated, which means VV is not the standard way to write 10. Use X instead.
For the common modern conversion system used by this calculator, 4 is written IV. However, historical Roman numeral use was not perfectly standardized. Older documents and inscriptions sometimes use additive forms such as IIII, and clock faces also commonly use IIII instead of IV. So it is more accurate to say that IIII is non-canonical in this calculator's standard modern notation, rather than saying it has never been used.
Clock-face tradition does not always follow modern textbook numeral conventions. IIII appears on many clocks and watches, mostly for historical and design reasons rather than a different value. Both IV and IIII can visually represent four in different contexts. For standard number conversion, this calculator outputs IV.
IC looks arithmetically like 99, but it is not standard notation. The canonical form for 99 is XCIX.
| Entered | Status | Canonical Form |
|---|---|---|
| IC | Not standard modern notation | XCIX (99) |
The familiar Roman numeral system does not have a standard symbol for zero comparable to the digit 0. For that reason, the standard converter rejects 0. It does not invent a later or historical notation as though it were part of the ordinary classical symbol set.
The basic Roman numeral system was not designed with the modern negative-number notation used in arithmetic. This calculator's standard converter supports positive whole numbers only.
The familiar modern letter-only form becomes less standardized beyond MMMCMXCIX, which is 3,999. Historical and extended systems can use devices such as overlines, additional symbols, or parenthetical forms. Those conventions are not uniform enough to treat any one method as the only universal answer, so this calculator keeps its standard converter at 1 to 3,999.
Break it down: 2,000 is MM, 20 is XX, and 6 is VI. Combined, that is MMXXVI. So 2026 equals MMXXVI.
Convert each numeric part separately. For October 6, 2026, the month is 10 (X), the day is 6 (VI), and the year is 2026 (MMXXVI). A Roman numeral date can be displayed as X / VI / MMXXVI when using month/day/year ordering. Other countries commonly use day/month/year, so the calculator clearly labels which ordering it used.
Yes, as a decorative representation, but date ordering matters. For example, 03/04/2000 could mean March 4 or 3 April depending on location. Date mode above shows the month name in the input and labels the output order to avoid ambiguity.
MM is 2,000, XX is 20, and VI is 6, for a total of 2,026.
A basic parser may incorrectly accept IC as 99 because I appears before C. But standard modern notation uses XCIX. Likewise, IL is not the canonical form for 49; the standard form is XLIX. A high-quality converter tells the user when a sequence can be arithmetically interpreted but is not standard notation, which is exactly what Check mode and Roman Numeral to Number mode do above: they parse the candidate, convert the resulting value back through the canonical number-to-Roman function, and compare the two forms.
The Roman numeral rules taught today are a standardized modern convention. Historical documents can contain variants. The National Archives (UK) provides examples of older additive and manuscript forms that differ from modern classroom conventions, which matters for anyone using this calculator while reading old records, monuments, historic dates, or manuscripts. The converter distinguishes standard modern notation from historical variation rather than treating every older form as a simple error.
Our ordinary decimal number system uses place value and zero. Roman numerals do not work the same way. That is why 1,994 can be written compactly in decimal digits, while the Roman representation MCMXCIV must combine symbol values. The two systems represent the same number using different notation.
Use this Roman Numeral Converter when converting between Roman numerals and ordinary whole numbers. Use the Date Calculator for calendar arithmetic, and the Unit Converter for measurement conversions. This tool is a notation converter, not a measurement calculator.
Modern Roman numerals use seven main symbols: I, V, X, L, C, D, and M. They combine through addition and six standard subtractive pairs. This calculator converts in both directions, validates canonical notation, explains the steps, handles Roman numeral dates, and clearly distinguishes standard modern rules from historical variations.
The examples below use the exact same engine as the calculator above, computed live in JavaScript so they always match what the calculator itself returns.
| Number | Roman Numeral | Number | Roman Numeral |
|---|
What is 1999 written as a Roman numeral, and why is it not written as the number of I's and X's you might first guess?
1999 breaks down as 1,000 + 900 + 90 + 9, which is M + CM + XC + IX = MCMXCIX. The standard form always uses the six subtractive pairs rather than long runs of repeated letters.
I want to convert between numbers and Roman numerals, or check whether a numeral is standard notation. (this page)
I want to add, subtract, or find the difference between calendar dates.
I want to convert between units of measurement, such as length, weight, or volume.
I want other general math tools and converters.
Roman numerals are a number-writing system built from seven letters: I, V, X, L, C, D, and M. They are still used today for clock faces, book chapters, monarchs and popes, movie sequels, and decorative dates.
The seven symbols are I (1), V (5), X (10), L (50), C (100), D (500), and M (1,000).
Roman numerals combine symbols through addition and subtraction. Symbols are normally added left to right, but when a smaller value appears directly before a larger one, it is subtracted instead, as in IV for 4.
IV means 4. The I before V signals subtraction: 5 minus 1 equals 4.
IX means 9. The I before X signals subtraction: 10 minus 1 equals 9.
XIV means 14. X is 10 and IV is 4, so 10 plus 4 equals 14.
XIX means 19. X is 10 and IX is 9, so 10 plus 9 equals 19.
XL means 40. L is 50, and X placed before it subtracts 10, so 50 minus 10 equals 40.
XLIV means 44. XL is 40 and IV is 4, so 40 plus 4 equals 44.
XC means 90. C is 100, and X placed before it subtracts 10, so 100 minus 10 equals 90.
XCIX means 99. XC is 90 and IX is 9, so 90 plus 9 equals 99. This is the standard form for 99, not IC.
CD means 400. D is 500, and C placed before it subtracts 100, so 500 minus 100 equals 400.
CM means 900. M is 1,000, and C placed before it subtracts 100, so 1,000 minus 100 equals 900.
MCMXCIV means 1,994. M is 1,000, CM is 900, XC is 90, and IV is 4, for a total of 1,994.
MMXXVI means 2,026. MM is 2,000, XX is 20, and VI is 6, for a total of 2,026.
Break the number into standard value pieces from largest to smallest, such as 1,000, 900, 90, and 4 for 1,994, then convert each piece to its symbol and combine them: MCMXCIV.
Read the numeral using the standard symbol values and valid subtractive pairs, add the value of each piece, and total them. This calculator also checks whether the numeral is standard modern notation rather than just computing arithmetic from any letter order.
Only I, X, and C are used subtractively, and only in specific pairs: I before V or X, X before L or C, and C before D or M.
IC is not standard modern notation because I is not permitted to subtract from C directly. Ninety is XC and nine is IX, so 99 is written XCIX.
IL is not standard modern notation because I cannot subtract from L. Forty is XL and nine is IX, so 49 is written XLIX.
I, X, C, and M can repeat up to three times in a row, as in III, XXX, CCC, and MMM. V, L, and D are not repeated in standard modern notation.
Standard modern notation never repeats V, L, or D. Ten is written as X rather than VV, because repeating those symbols is not part of the common convention.
IIII is not the standard modern form for 4 in this converter, which uses IV. Historical inscriptions and clock faces can use IIII, so this calculator flags it as non-canonical rather than simply wrong.
Clock-face tradition does not always follow modern textbook convention. Many clocks and watches use IIII instead of IV for design and historical reasons, not because the value is different.
For standard modern number conversion, this calculator outputs IV. IIII can still appear in historical documents and on clock faces, representing the same value in a different style.
No. The familiar Roman numeral system has no standard symbol for zero comparable to the digit 0, so this calculator does not support converting zero.
No. The basic Roman numeral system was not designed with modern negative-number notation, so this calculator supports positive whole numbers only.
2,000 is MM, 20 is XX, and 6 is VI, so 2026 is written MMXXVI.
Convert the month, day, and year separately and arrange them in your preferred order, such as month/day/year or day/month/year. Because date order varies by country, it is best to label which order you used.
Enter the month, day, and year into Date mode. Each part is converted separately, for example October 6, 2026 becomes X / VI / MMXXVI in month, day, year order.
The familiar letter-only system becomes less standardized above 3,999 (MMMCMXCIX). Historical and extended systems use devices such as overlines, but there is no single universal method, so this calculator keeps its standard range at 1 to 3,999.
Within this calculator's standard range, the largest value is 3,999, written MMMCMXCIX.
No. Historical Roman inscriptions and manuscripts were not always consistent with the modern textbook conventions taught today, and forms such as IIII appear in older records.
Use Check mode above. It parses your numeral, converts the resulting number back into canonical Roman numerals, and compares the two forms. If they differ, the numeral is not standard notation, and a canonical suggestion is shown.