This free Roman numeral converter changes numbers into Roman numerals and Roman numerals into numbers, with strict checks. It also converts whole dates, which makes it handy for tattoos, invitations and anniversaries.
- How to use the Roman numeral converter
- The rules of Roman numerals
- Key numerals at a glance
- Strict validation
- Years in Roman numerals
- Dates and tattoo tips
- Where Roman numerals still appear
- FAQ
- Related tools
How to use the Roman numeral converter
- To convert a number, type a whole number from 1 to 3999. The Roman numeral appears straight away.
- To convert a numeral, type it into the Roman box. You get the number, or a clear reason if the numeral is not valid.
- For a date, enter it as MM.DD.YYYY or DD.MM.YYYY, choose the order you used and pick the separator you want between the parts.
- Copy the result for your document, invitation, tattoo design or homework.
Everything runs in your browser. Nothing is uploaded, and you do not need an account.
The rules of Roman numerals
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. You add the values of the letters from left to right. XVI is 10 plus 5 plus 1, which makes 16.
A symbol can appear up to three times in a row. III is 3, but 4 is not IIII in the standard system.
Putting a smaller symbol before a larger one subtracts it. IV is 4 and IX is 9.
I may come before V and X, X before L and C, and C before D and M. IC for 99 is not valid. Write XCIX.
You never write VV for 10, and you never use V, L or D as the smaller symbol in a pair.
Key numerals at a glance
| Number | Roman numeral | How it is built |
|---|---|---|
| 1 | I | One stroke |
| 4 | IV | 5 minus 1, so I before V |
| 5 | V | Basic symbol |
| 9 | IX | 10 minus 1, so I before X |
| 10 | X | Basic symbol |
| 40 | XL | 50 minus 10 |
| 50 | L | Basic symbol |
| 90 | XC | 100 minus 10 |
| 100 | C | Basic symbol |
| 400 | CD | 500 minus 100 |
| 500 | D | Basic symbol |
| 900 | CM | 1000 minus 100 |
| 1000 | M | Basic symbol |
| 3999 | MMMCMXCIX | Largest standard value |
Notice that the pattern of 1, 4, 5 and 9 repeats in every power of ten. Once you know I, IV, V and IX, the same shapes appear with X, XL, L and XC, and again with C, CD, D and CM.
Strict validation and what it tells you
Many converters happily turn nonsense into a number. This one checks the numeral against the standard rules and tells you what went wrong. If you enter IIII, it explains that a symbol repeats too many times in a row. If you enter VX or IC, it points out that the subtraction is not allowed. If you type a character that is not a Roman symbol, it says so.
This helps when you are checking an inscription, a clock face or an answer on a worksheet. Some clocks do show IIII for 4, as a design tradition, but it is not part of the standard rules the converter checks against. The upper limit is 3999 because the standard letters have no symbol for 5000, and there is no Roman numeral for zero.
Years in Roman numerals
A year is just a big number, so you build it from the thousands down. The year 2026 is two thousands (MM), two tens (XX) and a six (VI), giving MMXXVI. Here are some years people commonly look up.
| Year | Roman numeral | Parts |
|---|---|---|
| 1999 | MCMXCIX | M CM XC IX |
| 2000 | MM | M M |
| 2024 | MMXXIV | MM XX IV |
| 2025 | MMXXV | MM XX V |
| 2026 | MMXXVI | MM XX VI |
| 2030 | MMXXX | MM XXX |
Film studios, universities and old buildings like Roman years because they look formal. If you are working on a copyright line or a plaque, always check the result with the converter before you send it to print.
Dates in Roman numerals and tattoo tips
A date in Roman numerals is written by converting the day, the month and the year separately and joining them with a separator. The day and month are small numbers, so they are short. For example, 14.02.2026 in day, month, year order becomes XIV.II.MMXXVI. A birthday of 07.03.1990 in month, day, year order becomes VII.III.MCMXC.
The order matters. Christmas 2026 is XII.XXV.MMXXVI when written month first and XXV.XII.MMXXVI when written day first. Both are correct, but only for the right convention, so choose the format that your readers use before you copy.
Planning a tattoo? Convert the date, then ask a friend to read it back to you, and have the artist confirm the letters on the stencil before the needle starts. A wrong letter is permanent. Decide in advance which separator you want, and remember that dots, dashes and spaces change the look.
Other good habits: check that the day and month are in the order you intend, say the date out loud once, and keep a screenshot of the final text with you for the appointment.
Where Roman numerals still appear
You will meet them on clock faces, in book chapters and prefaces, in film and TV copyright years, for sports events such as the Super Bowl, for monarchs and popes such as Elizabeth II, and in outlines. That is why the converter handles both directions. You might need to read a numeral on a building, or write one for a title page.
Frequently asked questions
How do I convert a number to a Roman numeral?
Type a whole number from 1 to 3999 into the number box and the Roman numeral appears at once. The tool breaks the number into thousands, hundreds, tens and ones, then writes each part with the standard symbols, using the subtractive forms such as IV and IX.
What is 2026 in Roman numerals?
2026 is MMXXVI. Two thousands give MM, two tens give XX and the six gives VI. Join them and you get MMXXVI. The same method works for any year, such as 1999, which is MCMXCIX. You can check any other year by typing it into the number box, up to 3999.
Why does the converter stop at 3999?
The standard Roman letters give no symbol for 5000, and you cannot repeat M more than three times in a row. That makes MMMCMXCIX, or 3999, the largest value in the usual system. Larger numbers need extensions such as an overline.
How do I write a date in Roman numerals?
Convert the day, month and year separately, then join them with a separator. Enter the date as MM.DD.YYYY or DD.MM.YYYY, pick the order you used and choose the separator. For example, 14.02.2026 becomes XIV.II.MMXXVI. Keep the same order your readers use, since day first and month first read differently.
Why is IIII not accepted?
The standard rules allow a symbol to repeat only three times in a row, and 4 is written IV. The converter checks against those rules and tells you why a numeral fails. Some clock faces use IIII as a tradition, but it is not standard.
Is there a Roman numeral for zero?
No. The Roman system had no symbol for zero, and ancient writers expressed the idea of nothing in words instead. The converter accepts numbers from 1 upward. Use a number from 1 to 3999 to get a valid result, then copy it.
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