Convert standard numbers to Roman numerals or decode Roman numerals back into numbers. The converter updates instantly as you type and checks decoded numerals for valid, canonical formatting.
Encode and decode modes
Use the mode toggle on the input pane to flip between directions. When set to Number, entering 42 yields XLII. When set to Roman, entering MMXXV yields 2025.
Because the traditional Roman numeral system lacks a symbol for zero and requires overlines for values of 4,000 or greater, the accepted conversion range is strictly 1 to 3999.
Batch processing
Turn on the Batch by newline option to process a column of values at once, placing one item per line. Enable Trim lines to strip invisible whitespace or trailing spaces from pasted lists.
Each line is processed independently. If you include an out-of-range number or an invalid Roman character, the tool will mark that specific line with an error while continuing to convert the rest of the list. Use the copy button to grab the results.