Skip to content
OneKitly
Sign up · Sign in

Roman numeral converter

Convert numbers to Roman numerals and back, one per line. Only the strict subtractive form counts: IIII, VV and IM are rejected, and the range is 1–3999.

Related tools

All Web & network tools →
Roman Numeral Math SolverAdd, subtract, multiply or divide Roman numerals (or Arabic 1–3999): parse each value, show the Arabic working and format the result back to a Roman numeral, with division quotient and remainder.ASCII code converterConvert text to ASCII/Unicode code points and back.Number base converterConvert numbers between all 35 bases, exactly, with two's complement.Programming case converterConvert identifiers between camelCase, snake_case, kebab-case, PascalCase and CONSTANT_CASE, one per line. Runs of capitals split correctly: parseHTTPResponse becomes parse_http_response.Column extractorExtract a single column from delimited data (CSV, TSV…). Works on a pasted block or on a file you drop in.Delimiter converterSwap the delimiter of your data — comma, tab, semicolon, pipe or space. Drop a file in rather than pasting it — it is read in your browser and never uploaded.DNS LookupScan a domain on two resolvers at once and see where they disagree.Extract text between delimitersPull out every piece of text that sits between a start and an end marker. Takes a whole file, so a long log does not have to go through the clipboard.

Roman numeral converter is free to use as often as you like, directly from this page. It sits under Web & network in our catalogue, alongside Roman Numeral Math Solver and ASCII code converter.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What does Roman numeral converter do?

Convert numbers to Roman numerals and back, one per line. Only the strict subtractive form counts: IIII, VV and IM are rejected, and the range is 1–3999.

When would I actually use this?

Getting usable data out of something that was never meant to be parsed: pulling every address out of a pasted thread, turning a column of lines into a JSON array or an SQL IN clause, renaming a hundred identifiers from snake_case to camelCase in one pass.

What is the most common mistake?

Trusting an extraction to be exhaustive. A pattern that catches every address in the sample will still miss the one wrapped across a line break, the one written with a display name, and the one an email client turned into a link — count what came out against what you expected before you use the list.

How is Roman numeral converter different from Roman Numeral Math Solver?

They sit next to each other but answer different questions. Roman Numeral Math Solver: add, subtract, multiply or divide Roman numerals (or Arabic 1–3999): parse each value, show the Arabic working and format the result back to a Roman numeral, with division quotient and remainder. Pick whichever matches what you're starting from — both are free.

Where do the figures come from?

Extraction runs on patterns, not on a parser: it recognises the common shapes of an address, a URL or an IP rather than validating them against their specification. That is the right trade for a paste, and the wrong one for input you are about to store.

Further reading

All guides →
ExplainerRoman Numerals ExplainedSeven letters, added or subtracted. Here's what each stands for, how the subtractive pairs work, how to write any number, and where they still appear.ExplainerSemicolon, Tab, Pipe: Choosing a Delimiter That Survives the TripWhy the reader's language decides the delimiter, what the converter does to the quoting when you switch, what the sep= first line really is, and the count of quoted cells on the same export written five ways.ComparisoncamelCase, snake_case, kebab-case: Which One, and Why You Rarely Get to ChooseThe conventions are not taste. A hyphen is the minus operator, so kebab-case cannot be an identifier in most languages - which is exactly why CSS and URLs use it. Plus the acronym round-trip that silently corrupts names, and the rule that fixes it.ExplainerBig O Notation for Beginners: O(1), O(n), O(n squared), and O(log n) ExplainedBig O describes how an algorithm's work grows as input grows. Here is what O(1), O(n), O(n squared), and O(log n) mean and why the difference matters.ExplainerWhat Is UTF-8 and Unicode? Code Points, Byte Encoding, and Why UTF-8 WonUnicode assigns every character a code point; UTF-8 encodes those code points in one to four bytes. Here is how it works and why it beat the alternatives.ExplainerHow Subnet Masks Work: CIDR, Network Bits, and Usable HostsUnderstand how a subnet mask splits an IP address into network and host parts, what /24 means, and how to count usable hosts.