Guide
Roman numerals above 3,999
The seven letters only go up to M (1,000), and M can only be repeated three times. So the largest number you can write with plain letters is 3,999, MMMCMXCIX. Bigger numbers need an extra mark.
Why the limit is 3,999
Under today's rules, a letter can't repeat more than three times in a row, so four thousand can't be MMMM. And there's no letter worth 5,000 for M to sit in front of, the way C sits before M to make 900. You'll occasionally see MMMM on old documents, but it isn't standard.
The bar: multiply by 1,000
The usual solution is a horizontal bar over the letters, called a vinculum (Latin for a bond or chain). A bar multiplies whatever is under it by 1,000:
| Number | Roman numeral | How it works |
|---|---|---|
| 4,000 | IV | IV (4) × 1,000 |
| 5,000 | V | V (5) × 1,000 |
| 10,000 | X | X (10) × 1,000 |
| 50,000 | L | L (50) × 1,000 |
| 100,000 | C | C (100) × 1,000 |
| 1,000,000 | M | M (1,000) × 1,000 |
Mixing barred and plain letters
Write the thousands with a bar, then the rest as normal. Split the number at the thousands:
- 4,444: 4 thousands and 444, so IVCDXLIV.
- 12,345: 12 thousands and 345, so XIICCCXLV.
- 2,026,000: 2,026 thousands and nothing else, so MMXXVI.
- 3,999,999: the largest number this way, MMMCMXCIXCMXCIX.
One convention: numbers from 1,000 to 3,999 are still written with M, not with a bar. 3,000 is MMM, not a barred III.
How the Romans wrote thousands
The bar is a later, mostly medieval and modern habit. The Romans themselves often wrote 1,000 as CIↃ, an I wrapped in a C and a backwards C, and 500 as IↃ. Adding more rings multiplied by ten: CCIↃↃ for 10,000. The letter M for 1,000 is thought to have grown partly out of this symbol, and D for 500 from its right-hand half.
There was never one fixed system for very large numbers. Different writers used bars, frames and other marks, so you may see variations in old sources.
Typing big numerals today
A bar is hard to type. Three common workarounds:
- Brackets: put the barred part in brackets, like (IV)CC for 4,200. The converter accepts this.
- Combining overline: a special character that draws a line over the letter before it. When you copy a big numeral from the converter, it uses these, so the bar survives when pasted into most apps.
- Drawing it: in a design program or by hand, add a line over the letters. The tattoo preview and PNG downloads draw the bar for you.
Try it: type 12345 or (XII)CCCXLV into the converter.