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YFT
Client-side ProcessingUpdated 2026-02-11Report issue

Runs fully in your browser. Inputs stay on your device. See recent fixes on changelog.

Roman Numeral Converter

Convert between Roman numerals and decimal numbers.

FreeRuns in browserroman numeral converterroman to decimal

Supports values from 1 (I) to 3999 (MMMCMXCIX).

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Cmd/Ctrl+Enter Primary actionCmd/Ctrl+Shift+L Load sampleCmd/Ctrl+Shift+X Clear/resetCmd/Ctrl+Shift+C Copy result

About Roman Numeral Converter

Convert between Roman numerals and decimal numbers online for free. Supports values from 1 (I) to 3,999 (MMMCMXCIX). Instant bidirectional conversion. Implements standard encoding and decoding algorithms that produce output compatible with all major programming languages and platforms. Supports both encoding and decoding in a single interface. Everything runs client-side in your browser for maximum speed and privacy — no data is sent to any server, and no signup is required.

Related tools: Number to Words Converter, Ordinal Number Converter, Binary Converter

How to Use Roman Numeral Converter

  1. Enter text or data in the input field.
  2. Click Encode or Decode depending on your goal.
  3. Copy the output to your clipboard.

Frequently Asked Questions

What is Roman Numeral Converter?
Convert between Roman numerals and decimal numbers online for free. Supports values from 1 (I) to 3,999 (MMMCMXCIX). Instant bidirectional conversion.
What encoding standards are used?
This tool follows the official encoding specifications, including RFC standards where applicable. The implementation matches widely-used libraries so the output is compatible with other systems and programming languages.
Can I encode binary data?
The tool primarily handles text input, but many encoding formats such as Base64 are designed to represent binary data as text. You can paste Base64-encoded binary data for decoding or encode text into a binary-safe format.
Is the encoding reversible?
Yes, all encoding operations provided by this tool are fully reversible. You can encode text and then decode it back to get the exact original content without any data loss.
Is Roman Numeral Converter free to use?
Yes, encoding and decoding are completely free with no usage limits. The tool runs in your browser and requires no registration.
Is my data safe when using Roman Numeral Converter?
Yes, all encoding and decoding happens locally in your browser. No data leaves your device, so your input remains completely private.

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Number to Words Converter
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Ordinal Number Converter
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Binary Converter
Convert numbers between binary, decimal, hex, and octal.