TextArray
100% local

Roman numeral converter

Convert numbers to Roman numerals and Roman numerals back to numbers, one per line.

Input
Output
Related tools
Number to wordsNumbersNumber sequence generatorNumbersRandom number generatorRandom generatorsHex to text and backEncoding & conversion
Roman numeral converter
Paste a number and get its Roman numeral, or paste a Roman numeral and read it back as digits. The converter works in both directions and decides which one you need from the input itself, so a list that mixes MMXXIV and 1999 comes out right without any switching.
Bulk conversion is the point: put one value per line and the whole column is converted at once. That matches where Roman numerals still turn up — years in film credits and copyright lines, chapter and outline numbering, monarchs and popes (Louis XIV), inscriptions on monuments and cornerstones, the count of Olympiads and Super Bowls, and the page numbers in a book's front matter. The lowercase option exists for that last case: the output reads i, ii, iii instead of I, II, III. Blank lines stay blank, so a converted column still lines up with the original row by row.
Validation is strict rather than forgiving. IIII, VIIII, VX and IC show up often enough, but they are not standard notation, so the tool names the line and explains what is wrong instead of quietly guessing a value. The range is 1 to 3999: classical notation has no zero, no sign, and nothing above MMMCMXCIX without overlines that plain text cannot carry. As a reminder, the building blocks are I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000, and a smaller symbol placed before a larger one is subtracted.
Everything runs in your browser and no number is uploaded anywhere. Copy the result, download it as a .txt file, or move it back to the input to convert it straight back and check the round trip.
FAQ
What range does the converter cover?
One to 3999. Standard Roman notation has no zero and no minus sign, and anything above MMMCMXCIX needs overlines that plain text cannot represent.
Why is IIII rejected?
Because standard notation subtracts instead of repeating: four is IV. IIII appears on clock faces and in some inscriptions, but the tool validates strictly and names the line rather than guessing what you meant.
Can I convert a whole list at once?
Yes. Put one value per line and every line is converted. Blank lines stay blank, so a column pasted from a spreadsheet keeps its alignment.
Does it handle lowercase Roman numerals?
Lowercase input such as mcmxc is read normally. Turn on the lowercase option to write the output as i, ii, iii — the usual style for front-matter page numbers.
Is my text uploaded anywhere?
No. The conversion runs entirely in your browser and nothing you paste leaves your device.