Number to Roman Numeral Converter

Roman numerals turn up exactly where modern notation does not reach: on movie posters, building cornerstones, monarch crowns and the year marks of classic cars. The system is only seven symbols deep — I, V, X, L, C, D and M — but the subtractive rule makes it easy to stumble: 4 is IV not IIII, 40 is XL not XXXX, and 1999 is MCMXCIX, a value few people can write from memory.

Number to Roman Numeral Converter applies the classic rules exactly, for single values or whole batches. Standard mode covers 1 to 3,999 — the entire traditional range — and extended mode continues beyond it with the parenthesized-thousands notation, writing 4,000 as (IV) and 12,345 as (XII)CCCXLV, with 0 as N. Every result follows the greedy subtractive algorithm, so the output is always canonical and always reversible. Everything runs in your browser; nothing is uploaded.

• Instant conversion: Type any number and the Roman form appears as you type.
• Standard mode: Exclusive 1–3,999 coverage using classic symbol rules.
• Extended mode: Parenthesized thousands for any size — 4,000 as (IV), 1234567 as ((I)CCXXXIV)DLXVII.
• Zero as N: The late-Roman nulla symbol for null, available in extended mode.
• Batch conversion: Up to 10,000 values, with out-of-range and invalid entries flagged per line.
• Canonical output: The greedy subtractive algorithm guarantees IV over IIII and IX over VIIII.
• Input grouping: Accepts 1,999 style input with thousand separators.
• Reference tab: Full symbol table, subtractive pairs and extended-mode examples.
• Copy or download: Take the Roman list to the clipboard or save it as a text file.
• Free and private: Everything runs locally in the browser; nothing is uploaded or stored.

1. Choose the mode. Standard for the classic 1 to 3,999 range; Extended when numbers go beyond 3,999 or include zero.
2. Enter your numbers — one per line, or a batch separated by commas or spaces.
3. Read the results — each Arabic value is matched with its Roman form.
4. Switch modes if needed — a value over 3,999 is rejected in standard mode with a clear message.
5. Copy or download the Roman list for documents, outlines or labels.

Example 1 — A year. Enter 2025. The tool returns MMXXV — the canonical form used on cornerstone dates and movie copyright lines.

Example 2 — The tricky subtractives. Enter 4, 9, 40 and 90. The output is IV, IX, XL and XC — the four pairs that constantly trip up hand conversion.

Example 3 — A book outline. Enter 1999. The tool writes MCMXCIX in one click, the exact form used in the front matter of books.

Example 4 — Above the classical range. Switch to extended mode and enter 45231. The result is (XLV)CCXXXI — forty-five thousand two hundred thirty-one written with a parenthesized thousands group.

Example 5 — Mixed batch. Paste 1, 5, 10, 50, 100, 500, 1000 together. The output is the complete symbol ladder — I, V, X, L, C, D, M — ready for a reference sheet.

• Exact classic rules: The subtractive algorithm writes IV, IX, XL, XC, CD and CM exactly as tradition demands.
• No ceiling once extended: Any size converts, with parenthesized thousands for values past 3,999.
• Batch speed: Ten thousand values in one run, each with its own clear error reporting.
• Zero finally handled: N for nulla when you need to represent nothing at all.
• Reversible and canonical: Every output passes the round-trip test back to its Arabic form.
• Private and free: Conversion happens entirely in the browser; nothing is uploaded, stored or logged.