Handytool
UtilityFreeRuns locally

Roman numeral converter

Convert numbers to Roman numerals and back, from 1 to 3,999,999 with overline (vinculum) notation, plus validation and a step-by-step breakdown.

Supports 1 to 3,999,999. Values above 3,999 use overline (vinculum) notation, where a bar over a symbol multiplies it by 1,000.

Result
The conversion appears here

Everything runs in your browser — your input is never uploaded.

About the Roman numeral converter

Roman numeral converter turns numbers into Roman numerals and decodes Roman numerals back into numbers, with automatic direction detection. It covers 1 to 3,999,999 — using the classic overline (vinculum) notation, where a bar above a numeral multiplies it by 1,000, for values above 3,999. Every conversion is validated and comes with a step-by-step breakdown so you can see exactly how the numeral adds up. All in your browser, nothing uploaded.

Roman numeral converter features

  • 01

    Both directions, auto-detected

    Type a number to get the numeral, or type a numeral to get the number — the tool detects which you entered and converts automatically.

  • 02

    Large numbers with overline

    Values above 3,999 use the vinculum: an overline over a symbol multiplies it by 1,000, extending the range up to 3,999,999.

  • 03

    Validation and breakdown

    Malformed or non-standard numerals are flagged, and a breakdown table shows each symbol's contribution so the result is easy to verify.

Roman numeral converter FAQ

How do I convert a number to Roman numerals?
Type the number (for example 2025) and the Roman numeral (MMXXV) appears instantly, along with a breakdown of how each symbol adds up.
How do I convert Roman numerals to a number?
Type the numeral, such as MCMLXXXIV, and the tool decodes it to 1984. It auto-detects that you entered a numeral and validates that it's well formed.
What is the largest number it supports?
3,999,999. Numbers above 3,999 use overline (vinculum) notation, where a bar over a symbol means times 1,000, so M with an overline equals 1,000,000.
Why does it say my numeral isn't standard?
The numeral parses to a value but isn't written in the canonical form (for example IIII instead of IV). The tool still shows the number but flags it so you can use the standard spelling.
Is my input sent anywhere?
No. Conversion happens entirely in your browser and nothing you enter is uploaded.

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