Roman Numeral Converter

Convert

Number

Roman numeral

Accept older and irregular forms — IIII, XXXX, VIIII and other additive spellings that appear on clock faces and inscriptions. Off by default, so malformed input is refused rather than guessed at.

The seven letters, and the six subtractive pairs

Symbol	Value	Symbol	Value

Standard Roman numerals stop at 3,999 (MMMCMXCIX), because there is no single letter for ten thousand and no more than three M may be written in a row. Above that this page uses the vinculum: a bar over a letter multiplies it by a thousand, so V̅ is 5,000 and X̅X̅I̅V̅ is 24,000. Everything runs in your browser and nothing is uploaded.

💡 Tip: both boxes are live and linked. Type a number on the left and the numeral appears on the right; type a numeral on the right and the number appears on the left. Nothing needs clicking, and the panel underneath shows exactly which pieces the answer was built from.

🧭 User Guide

Type into whichever box suits you. Digits on the left, letters on the right — lower case is fine, and commas and spaces are ignored.
Read the working out. Every numeral is shown as its component parts with their values, so MCMXCIV appears as M + CM + XC + IV and the sum is spelled out.
Watch for the refusals. Type something malformed and the page names the specific rule it breaks rather than giving a vague error — four repeats, a doubled V, an impossible subtraction.
Tick the box for older spellings if you are reading an inscription or a clock face, where IIII and VIIII genuinely appear. The page then tells you the modern spelling as well.
Go past 3,999 and the overline appears automatically. A bar over a letter multiplies it by a thousand.
Use the shortcuts for the current year, a random number to practise with, or to copy the numeral straight out.

📜 Numbers 1 to 100 in Roman numerals

The range people look up most often, in full.

No.	Roman	No.	Roman	No.	Roman	No.	Roman	No.	Roman
1	I	21	XXI	41	XLI	61	LXI	81	LXXXI
2	II	22	XXII	42	XLII	62	LXII	82	LXXXII
3	III	23	XXIII	43	XLIII	63	LXIII	83	LXXXIII
4	IV	24	XXIV	44	XLIV	64	LXIV	84	LXXXIV
5	V	25	XXV	45	XLV	65	LXV	85	LXXXV
6	VI	26	XXVI	46	XLVI	66	LXVI	86	LXXXVI
7	VII	27	XXVII	47	XLVII	67	LXVII	87	LXXXVII
8	VIII	28	XXVIII	48	XLVIII	68	LXVIII	88	LXXXVIII
9	IX	29	XXIX	49	XLIX	69	LXIX	89	LXXXIX
10	X	30	XXX	50	L	70	LXX	90	XC
11	XI	31	XXXI	51	LI	71	LXXI	91	XCI
12	XII	32	XXXII	52	LII	72	LXXII	92	XCII
13	XIII	33	XXXIII	53	LIII	73	LXXIII	93	XCIII
14	XIV	34	XXXIV	54	LIV	74	LXXIV	94	XCIV
15	XV	35	XXXV	55	LV	75	LXXV	95	XCV
16	XVI	36	XXXVI	56	LVI	76	LXXVI	96	XCVI
17	XVII	37	XXXVII	57	LVII	77	LXXVII	97	XCVII
18	XVIII	38	XXXVIII	58	LVIII	78	LXXVIII	98	XCVIII
19	XIX	39	XXXIX	59	LIX	79	LXXIX	99	XCIX
20	XX	40	XL	60	LX	80	LXXX	100	C

⚖ Four rules that decide whether a numeral is well formed

Roman numerals look permissive and are not. These four constraints rule out almost every mistake.

Three in a row, at most

I, X, C and M may repeat up to three times. V, L and D never repeat at all.

So 4 is IV rather than IIII, and 40 is XL rather than XXXX. VV is meaningless because two fives are simply X, and the same reasoning rules out LL and DD. This single rule is behind most rejected input.

Only six subtractions exist

IV, IX, XL, XC, CD and CM. There are no others.

A letter may only be taken from the next two values above it, which is why IC for 99 is wrong — it has to be XCIX. Nor may V, L or D ever be subtracted, so VX and LC are not numerals at all, however sensible they look.

Largest first, always

Thousands, then hundreds, then tens, then units, each descending.

The only time a smaller letter precedes a larger one is inside one of those six subtractive pairs. MCMXCIV works because it reads as M, then CM, then XC, then IV — four descending groups, not a jumble.

One spelling per number

Every value from 1 to 3,999 has exactly one correct modern form.

That is what makes the conversion reversible: encode a number, decode the result, and you are guaranteed the number you started with. This page checks all 3,999 of them, in both directions, before it ships.

About the Roman Numeral Converter

Two linked boxes that translate between ordinary numbers and Roman numerals in either direction, show the working, and refuse malformed input with a reason instead of a shrug. It handles 1 to 3,999 in the standard letters and up to 3,999,999 using the overline that stands for a thousand.

Why the system stops at 3,999

Because it ran out of letters, and never invented more.

The largest symbol is M for a thousand, and no letter may appear more than three times in a row, so MMM — 3,000 — plus the largest possible remainder, CMXCIX for 999, gives MMMCMXCIX and there is nowhere left to go. There is no symbol for ten thousand, and no zero anywhere in the system, which is one reason arithmetic in Roman numerals is so awkward and why the positional digits we borrowed from India displaced them for calculation.

The workaround the Romans themselves used was a bar, called a vinculum, drawn over a letter to multiply it by a thousand. A barred V is five thousand, a barred X is ten thousand. This page writes those automatically above 3,999 and reads them back, which is why its ceiling is 3,999,999 — a barred MMM plus MMMCMXCIX.

What counts as an error, and what is merely old

A distinction most converters skip entirely.

IIII is not a typing mistake. It is the older additive spelling, and it is what you will find on the vast majority of clock and watch faces, where IIII balances the VIII opposite it far better than IV does. Inscriptions use VIIII for nine and XXXX for forty for the same reason. None of that is modern standard form, and none of it should be produced by a converter by default.

So this page refuses those spellings unless you ask for them. Tick the box and it will read IIII as four — and tell you that the standard spelling is IV, so you know which one to use where. That is a different thing from IC or VX, which are not older forms but simply are not numerals, and are refused either way.

Reading the breakdown

Every answer shows its parts.

Convert 1,994 and the panel gives you M, CM, XC and IV with the values 1000, 900, 90 and 4, and the sum written out. That is the whole method: take the largest value that fits, write it, subtract it, repeat. Seeing it laid out is usually enough to make the rules obvious, which is why the panel is there rather than hidden behind a button.

Where people actually need this

More often than the system’s age suggests.

Dates carved on buildings and printed in film credits, chapter and appendix numbers, monarch and pope regnal numbers, the outline levels in a legal document, Super Bowl and Olympiad numbering, clock faces, and the date tattoos people want spelled correctly before anything permanent happens. Students meet them in primary arithmetic; anyone restoring an old building meets them on the datestone.

Two nearby tools.

For conversions between binary, octal, decimal and hexadecimal, use the Digit Converter. For the numeric value of letters and symbols in computing rather than in Latin, see the Text and ASCII Converter.

Frequently Asked Questions

How do I write 2026 in Roman numerals?

MMXXVI.

It breaks down as MM for 2,000, XX for 20, V for 5 and I for 1. The This year button fills it in for you, and the panel underneath shows those four pieces.

Why do clocks show IIII instead of IV?

Symmetry, mostly — and habit older than the modern rule.

IIII has four characters, which balances the VIII directly opposite it on the dial, and it means the numerals either side of the six are visually even. Several other explanations circulate, involving casting moulds and a king’s preference, but the balance argument is the one that holds up when you look at surviving dials. Tick the older-forms box on this page and IIII will be read as four.

What is the largest number Roman numerals can express?

3,999 with the ordinary letters; 3,999,999 once bars are allowed.

MMMCMXCIX is the ceiling without a vinculum. Add the bar, which multiplies by a thousand, and the practical limit becomes a barred MMMCMXCIX followed by MMMCMXCIX.

Is there a Roman numeral for zero?

No. The system has no symbol for nothing at all.

Medieval scribes writing in Latin used the word nulla when they needed to express it, but that is a word, not a numeral. The absence is not an oversight so much as a consequence: a tally-based system never needs a placeholder, and it is positional notation that makes zero indispensable.

What does XLII come to?

42. XL is 40 and II is 2.

The trap is reading XL as 10 + 50. Because the X precedes a larger letter it is subtracted, giving 50 − 10. Type it into the box on the right and the breakdown makes the grouping visible.

How should a date be written for a tattoo or an inscription?

Convert each part separately and join them with full stops or hyphens.

For 9 March 2004, that is IX · III · MMIV. Convert the day, the month and the year one at a time on this page rather than converting 9032004 as a single number, which would give you something entirely different. Check it twice before anything permanent.

Does the page work offline, and is anything sent anywhere?

It works offline once loaded, and nothing is sent anywhere.

All the conversion happens in your browser. There is no sign-up, no limit, and no external file of any kind is fetched — this version deliberately removed the icon font the previous one loaded from a third-party network.