Roman Numeral Converter

How the Roman numeral converter works

Type a number and get its Roman numeral. Type a Roman numeral and get the number back. The converter detects which one you typed, so 2026 becomes MMXXVI and mcmxciv becomes 1994 without touching a setting. If you prefer to be explicit, the mode pills lock the direction to Number to Roman or Roman to Number, and the Date pill turns a calendar date into the dotted numeral strings people use for anniversaries, invitations and tattoos.

Every result comes with a step-by-step breakdown. Convert 1994 and the line under the output reads 1994 = 1000 + 900 + 90 + 4 → M + CM + XC + IV = MCMXCIV, so you can see exactly which symbol stands for which part of the number. Convert a numeral and you get the same chain in reverse. That breakdown is the fastest way to check a numeral you found on a building, a clock or a film credit, and it doubles as a study aid for anyone learning the system.

The converter is strict on purpose. Plenty of numerals that look plausible are not standard: IIII, VV, IC or MMMM. Instead of guessing what you meant, the tool rejects them, names the rule they break and shows the correct form. It accepts lowercase input, ignores stray spaces and always answers in uppercase. You can paste one value per line to convert a whole list at once. Everything runs locally in your browser, so nothing you type is uploaded or stored.

The seven Roman numeral symbols

Every Roman numeral is built from seven capital letters. Learn this table and you can read almost any numeral you meet.

Symbol	Value	Example
I	1	III = 3
V	5	VIII = 8
X	10	XX = 20
L	50	LX = 60
C	100	CC = 200
D	500	DC = 600
M	1,000	MM = 2,000

Notice the rhythm: the values climb in a repeating one, five, ten pattern. I, X, C and M are the powers of ten, and V, L and D are the fives in between. That rhythm is why the whole system can be read one decimal place at a time, and it is exactly how this converter works internally: thousands first, then hundreds, then tens, then ones.

The rules: addition, subtraction and repetition

Roman numerals are read from left to right, adding values as you go, largest first. MDCLXVI is 1000 + 500 + 100 + 50 + 10 + 5 + 1, which is 1666. When a smaller symbol sits in front of a larger one, it is subtracted instead: IV is 5 minus 1, which is 4. Four short rules keep the modern standard form unambiguous.

• Repeat I, X, C and M at most three times in a row. III is 3, and 4 is written IV, not IIII.
• Never repeat V, L or D. VV would simply be X, LL would be C and DD would be M.
• Subtract only I, X or C, and only from the next two symbols up. I goes before V and X, X goes before L and C, and C goes before D and M. Those six pairs (IV, IX, XL, XC, CD and CM) are the only subtractive pairs in the standard form.
• Never subtract V, L or D. VX is not 5; it is just V.

The subtraction rule is the one people break most often. It feels natural to write 99 as IC, one less than a hundred, but I may only precede V or X, so 99 is built place by place instead: 90 is XC and 9 is IX, giving XCIX. The same logic turns 49 into XLIX rather than IL, and 999 into CMXCIX rather than IM. When in doubt, split the number into thousands, hundreds, tens and ones, convert each part on its own, and write the parts side by side. That method never produces an invalid numeral.

These rules are a later standardization rather than ancient law. As Wolfram MathWorld notes, the Romans hardly ever used subtraction, and the practice became popular in Europe after the invention of the printing press. That is why you still see IIII on many clock faces. The converter follows the modern standard form, the one used in publishing, schools and official documents today.

Roman numerals chart 1 to 100

The chart below covers every value from 1 to 100. Read across a row for consecutive numbers, or down a column to see how the tens change while the ones repeat.

Beyond 100 the pattern simply continues. These are the values people look up most often:

Number	Roman numeral
150	CL
200	CC
400	CD
500	D
900	CM
1000	M
1500	MD
1900	MCM
1999	MCMXCIX
2000	MM
2025	MMXXV
2026	MMXXVI
2027	MMXXVII
2030	MMXXX
3999	MMMCMXCIX

A quick tip for years: every year from 2000 to 2099 starts with MM, so you only need to convert the last two digits. 2026 is MM plus XXVI (26), giving MMXXVI. Years from 1900 to 1999 start with MCM, which is why so many film copyright lines from the twentieth century seem to begin the same way.

Dates in Roman numerals: birthdays, weddings and tattoos

The Date mode converts a full calendar date in one go. Pick a day with the calendar or type it (2026-09-23, 09/23/2026 and 23.09.2026 all work), then choose the order. MM.DD.YYYY is the usual order in the United States, DD.MM.YYYY is the order used across Europe and Latin America, and YYYY only gives just the year for a cornerstone, a book spine or a class ring. September 23, 2026 comes out as IX.XXIII.MMXXVI in month-first order and XXIII.IX.MMXXVI in day-first order.

The separator matters more than people expect, especially for engraving and tattoos. Dots are the classic choice and read cleanly at small sizes. A middle dot (·) looks elegant and echoes the interpuncts Roman stonecutters placed between words. Hyphens, slashes and plain spaces are also available. Whatever you choose, keep each part of the date as its own complete numeral: the day, the month and the year are converted separately and never run together, so XXIII.IX.MMXXVI can be read back without ambiguity.

Before you commit a date to skin, metal or stone, check it twice. Paste the finished numeral into the converter in Roman to Number mode, one part at a time, and make sure each piece reads back to the number you meant. It takes ten seconds and prevents the classic mistakes, like a stray I that turns 23 into 24 (XXIV) or a reversed pair that turns 9 into 11 (XI).

Large numbers and the vinculum

Standard Roman numerals top out at 3,999, written MMMCMXCIX, because M may repeat only three times. For bigger values, writers used the vinculum: a horizontal bar over a numeral that multiplies it by 1,000. V̅ is 5,000, X̅ is 10,000 and M̅ is one million. Wolfram MathWorld notes that the Romans occasionally used such a bar, and that in the Middle Ages it was called a titulus.

Tick Large numbers (vinculum) and the converter accepts values up to 3,999,999. The thousands are written with a bar and the remainder follows in ordinary numerals: 4,000 becomes I̅V̅, 12,500 becomes X̅I̅I̅D and 3,999,999 becomes M̅M̅M̅C̅M̅X̅C̅I̅X̅CMXCIX. Values below 4,000 keep using M, because MMM is the standard way to write 3,000.

On screen, the bar is the Unicode character U+0305, COMBINING OVERLINE, which the Unicode chart itself annotates as the vinculum. It attaches to the letter before it, so V followed by U+0305 displays as V̅. Rendering varies by font: if the bars look slightly offset, the text is still correct and will paste into documents that support combining marks. You can also paste overlined numerals into the converter to read them, as long as the vinculum option is on.

Common mistakes the converter catches

The validator rejects anything outside the standard form and explains the problem in plain words. These are the errors it sees most:

• IIII for 4. I can repeat only three times, so 4 is IV. The same rule turns XXXX into XL and CCCC into CD.
• VV, LL or DD. V, L and D are never repeated, because X, C and M already stand for those doubled values.
• IC, IL, XM and similar shortcuts. A symbol may only be subtracted from the next two symbols up, so 99 is XCIX, 49 is XLIX and 990 is CMXC.
• VX or LC. V, L and D are never subtracted.
• MMMM for 4,000. Standard numerals stop at 3,999. Turn on the vinculum and 4,000 is I̅V̅.
• Zero, negatives and decimals. The Roman system has no symbol for zero, no negative numbers and no decimal point, so the converter asks for a whole number from 1 upward.
• Out-of-order symbols. Strings like IIV or VIV are not standard even though each pair looks legal. The converter shows the value they add up to and the correct way to write it.

If you are checking a numeral from an old document, keep in mind that historical writing was looser than the modern standard, and an inscription may well use IIII or VIIII. The converter tells you the standard form, which is what you want for anything new you publish.

Where Roman numerals are still used

Roman numerals survive wherever a number should look formal, permanent or distinct from ordinary counting. Monarchs and popes carry them in their names: Charles III, Elizabeth II, Pope Leo XIV. The NFL numbers its championship games with them, so the February 2026 game was Super Bowl LX; the one exception was Super Bowl 50 in 2016, which used Arabic numerals. The Olympic Games are numbered too, and Paris 2024 was officially the Games of the XXXIII Olympiad.

In publishing, lowercase numerals (i, ii, iii, iv) number the front matter of a book, such as the preface and the table of contents, so that page 1 can start with the first chapter. Outlines and legal documents use I, II and III for top-level sections. Clock and watch faces use them for their classic look. Music theory labels chords with them, so I, IV and V are the tonic, subdominant and dominant. Chemistry uses them for oxidation states, as in iron(III) oxide. Film and television credits have long printed the copyright year in Roman numerals, which is exactly the kind of line this converter decodes in a second. For the history and the finer points, read Roman Numerals: The Complete Guide.

Frequently asked questions

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