Number to Roman Numerals Converter
Going the other way? Convert Roman numerals back to a number →
How do I convert a number to Roman numerals?
Roman numerals write 1987 as MCMLXXXVII. Work down one decimal place at a time: take the largest symbol value that fits, write it, subtract it, and carry on with what is left. Where a smaller symbol stands before a larger one it is subtracted instead, which is how 900 becomes CM.
- Type a whole number from 1 to 3999 into the box. A value outside that range is refused, with the reason.
- Read the figure one decimal place at a time, thousands first, then hundreds, tens and units.
- Write the standard form of each place: 1000 is M, 900 is CM, 80 is LXXX and 7 is VII.
- Join the places, largest first. The working under the box shows each place on its own line.
- Copy the result, or swap the direction to read a numeral back as a figure.
Roman Symbols and the Subtractive Forms
Seven symbols carry every value this converter writes, and six subtractive forms cover the places where a smaller symbol goes first. Only I, X and C are ever subtracted, and only from the next two larger symbols. That gives six subtractive forms and no others: IV, IX, XL, XC, CD, CM. The third column shows what a run of one symbol looks like, and which symbols never take one.
| Symbol | Value | In a run |
|---|---|---|
| I | 1 | III |
| V | 5 | never repeated |
| X | 10 | XXX |
| L | 50 | never repeated |
| C | 100 | CCC |
| D | 500 | never repeated |
| M | 1000 | MMM |
| Form | Value | How it reads |
|---|---|---|
| IV | 4 | 5 - 1 |
| IX | 9 | 10 - 1 |
| XL | 40 | 50 - 10 |
| XC | 90 | 100 - 10 |
| CD | 400 | 500 - 100 |
| CM | 900 | 1000 - 100 |
Worked Example: 1987 to Roman numerals
1987 splits into four decimal places, and each place has one standard form. The working below writes them out largest first, with the arithmetic behind each one.
Result: 1987 = MCMLXXXVII
Reading the four places back gives MCMLXXXVII, which is what the box above shows. The seeds below are the values the rest of this family works from, so every page shows the same numeral for the same figure.
- 1987 in Roman numerals: MCMLXXXVII; symbol by symbol: M 1000 + CM 900 + LXXX 80 + VII 7
- 3999 in Roman numerals: MMMCMXCIX
- 4 in Roman numerals: IV
Check it in reverse
To verify the result by hand, read the Roman numeral back as a figure and compare it with what you started from.
Worked examples: numbers to Roman numerals
Each example gives the value first, then the working. Select a value to load it in the converter.
What is 1, 2, 3, 4, 5, 6, 7, 8, 9 in Roman numerals?
From 1 to 9 the forms are 1 I, 2 II, 3 III, 4 IV, 5 V, 6 VI, 7 VII, 8 VIII, 9 IX.
I repeats up to three times, V is 5, and IV and IX are the two subtractive forms in this range.
What does 666 look like in Roman numerals?
666 is written DCLXVI.
Three places: 600 DC, 60 LX, 6 VI. Every symbol falls in value from left to right, so nothing is subtracted.
What is 69 in Roman numerals?
69 is written LXIX.
Two places: 60 LX, 9 IX. Joined largest first, that is LXIX.
What are the Roman numerals from 1 to 100?
The turning points are 1 I, 5 V, 10 X, 40 XL, 50 L, 90 XC, 100 C.
Everything between them is built by adding units to the form below it, or by subtracting one symbol from the next.
Every example above reverses exactly — add the same symbols back up to the number.
How Roman Numerals Are Built
The rules below are the ones this converter follows, and every value in the reference table is the one the widget uses. Where a value breaks a rule, the page names the rule instead of writing a numeral nobody uses.
Only I, X and C are ever subtracted, and only from the next two larger symbols. That gives six subtractive forms and no others: IV, IX, XL, XC, CD, CM.
I, X, C and M may stand up to three times in a row; V, L and D are never repeated.
Roman numerals have no symbol for zero and no place value: a symbol is worth the same wherever it stands. Writers who needed a zero used the Latin word nulla, and from about 725 the letter N.
With the seven standard symbols the largest value you can write is 3,999, MMMCMXCIX. Beyond that Roman numerals take a vinculum - an overline that multiplies the numeral by 1,000, so V with an overline is 5,000.
iToolHub writes Roman numerals in uppercase, in standard subtractive form, and accepts 1 to 3,999; it does not write overlines.
Roman numerals use seven letters: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1000.
Read a Roman numeral from left to right and add the symbol values; where a smaller symbol stands before a larger one, subtract it instead, so IV is 4 and IX is 9.
IV is the standard form of 4, but IIII is the older additive form and clock faces have used it since the late 14th century.
| What | Value |
|---|---|
| What kind of system it is | additive with limited subtraction; not positional |
| The subtractive forms | IV 4, IX 9, XL 40, XC 90, CD 400, CM 900 |
| Symbols that may be subtracted | I, X, C |
| Symbols that may repeat | I, X, C, M |
| How many times one may repeat | 3 |
| Symbols that never repeat | V, L, D |
| Symbol for zero | none |
| What writers used instead of zero | nulla (Dionysius Exiguus, 525); the letter N (Bede or a colleague, about 725) |
| Largest value with the standard symbols | 3999 |
| That value written out | MMMCMXCIX |
| What an overline multiplies by | 1000 |
| An overline in use | V with an overline is 5,000; XXV with an overline is 25,000 |
What Changes the Roman Numeral?
Three in a Row, and No More
I, X, C and M may stand up to three times in a row; V, L and D are never repeated. A fourth I is the older additive form, which this page does not write, and a run of five is refused outright.
Where the Symbols Run Out
With the seven standard symbols the largest value you can write is 3,999, MMMCMXCIX. Beyond that Roman numerals take a vinculum - an overline that multiplies the numeral by 1,000, so V with an overline is 5,000. This converter writes no overlines, so 4000 and above are refused with the reason rather than answered with a form the page cannot render.
Nothing for Nothing
Roman numerals have no symbol for zero and no place value: a symbol is worth the same wherever it stands. Writers who needed a zero used the Latin word nulla, and from about 725 the letter N. A figure of 0 therefore has no answer here, and the page says so.
Common Mistakes
- Writing IL for 49. Only I, X and C are ever subtracted, and only from the next two larger symbols, so 49 is XLIX.
- Repeating V, L or D. VV is not 10 and LL is not 100; the ten and the hundred have their own symbols.
- Expecting a value above 3999. The seven standard symbols stop there, and the overline that carries you past it is a mark this page does not write.
- Reading a numeral left to right and adding every symbol. CM is 900, not 1100, because the C stands before the M.
Frequently Asked Questions
What is "I love you" in Roman numerals?
It is not a conversion. A Roman numeral stands for one value, not for a phrase, and O, E and Y are not symbols at all. Turning each letter into a code is a different job with a different answer.
Can Roman numerals be written in lowercase?
You meet mcmlxxxvii in manuscripts and in the front matter of books. This page writes uppercase, and the other direction reads either case, so both spellings give the same figure.
What is 1000000 in Roman numerals?
The seven standard symbols stop at 3999. A million takes a vinculum, an overline that multiplies the numeral by 1000, and this converter does not write overlines, so it refuses the value and says why.
What is 0 in Roman numerals?
Nothing is written for it. The seven symbols carry no zero, and there is no place value for a zero to hold open. Writers who needed one used the Latin word nulla, and from about 725 the letter N, but neither is a numeral, so a figure of 0 is refused here.
Why is 4 written IV and not IIII?
IV is the standard form: the I stands before the V, so it is subtracted, and 5 minus 1 is 4. IIII is the older additive form and is not wrong. This page writes IV; the other direction reads both.
How many times can the same Roman numeral repeat?
I, X, C and M may stand up to three times in a row; V, L and D are never repeated. A fourth I is the older additive form, so IIII reads as 4 on the other page, and a fifth is refused.
Yes. The same value converts straight back in the Roman numerals to number direction.
Related Conversions
The rest of the family sits on the numeral converter index.