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Roman Numeral Converter Online Free - Bidirectional

Convert any number (1-3999) to Roman numerals or decode Roman numerals back to decimal. Includes reference table and popular years like 2024 (MMXXIV).

New
Browser-based
Browser-basedRuns in your browser

No file upload is required for the standard workflow. Processing happens in the current browser session unless you choose a separate account or export feature.

How it works

Roman Numeral Converter converts any integer from 1 to 3999 into Roman numerals, and decodes any Roman numeral back into its decimal value. Toggle between 'Number → Roman' and 'Roman → Number' modes. A reference table with all 13 base values (I, IV, V, IX, X, XL, L, XC, C, CD, D, CM, M) and a shortcut row of popular years make it fast to explore common conversions. All computation runs in your browser.

1. Upload / Input

Select the conversion direction: Number → Roman or Roman → Number.

2. Browser Process

Enter a number (1-3999) or a valid Roman numeral.

3. Save Output

The result appears instantly. Click Copy to use it.

Why Use This Tool

  • ✓Number to Roman numeral conversion (1-3999)
  • ✓Roman numeral to decimal conversion
  • ✓Bidirectional conversion with mode toggle
  • ✓Reference table for all 13 Roman numeral values
  • ✓Popular years shortcut buttons (2024, 2023, 2000, etc.)
  • ✓Validation of Roman numeral input
  • ✓Copy result button

Perfect For

  • 1Writing chapter numbers or page numbers in Roman numerals.
  • 2Decoding Roman numerals on clocks, buildings, or films.
  • 3Learning Roman numerals for academic or historical study.
  • 4Converting copyright years to Roman numeral format.

Processing & Safety Note

This tool page uses the browser-based workflow described above for standard use. Account saving, AI tools, downloaders, and Temp Mail have separate handling notes.

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Trust & Security Standards

Bidirectional Conversion

Convert numbers to Roman numerals and Roman numerals back to decimal in one tool.

Input Validation

Invalid Roman numeral strings are detected and an error is shown immediately.

Reference Table

All 13 subtractive notation values are displayed in a clickable reference table.

Browser-Only

Conversion runs entirely in JavaScript. No data is sent to a server.

FAQ

The converter supports Roman numerals from I (1) to MMMCMXCIX (3999). Values outside this range cannot be represented in standard Roman numerals.
Click the 'Roman → Number' tab, type the Roman numeral (e.g., MMXXIV), and the decimal equivalent appears instantly.
MMXXIV = 2024. MM = 2000, XX = 20, IV = 4.
The seven basic symbols are: I=1, V=5, X=10, L=50, C=100, D=500, M=1000. Subtractive pairs like IV (4), IX (9), XL (40), XC (90), CD (400), CM (900) are also used.
Subtractive notation (e.g., IV instead of IIII) was adopted for brevity and to avoid ambiguity. It limits repeating the same symbol more than three times in a row.

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