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Roman Numerals Converter

Convert Arabic numbers 1–3999 to Roman numerals and back. Live sync, strict validation, symbol breakdown, and a clickable chart.

PrivateIn your browserInstantUnlimited

Integers from 1 to 3999

M + M + X + X + V + I = 1000 + 1000 + 10 + 10 + 5 + 1 = 2026

How it works

1

Enter Arabic or Roman

Type a whole number from 1 to 3999, or a Roman numeral using I V X L C D M. Editing either side updates the other live.

2

Validate and break down

Only standard forms are accepted (IV not IIII, XC not IC). The breakdown shows how the numeral is built from symbols.

3

Copy or download

Copy either value, toggle lowercase Roman, or download a short text report with the breakdown.

What are Roman numerals?

Roman numerals use letters I, V, X, L, C, D, and M for 1, 5, 10, 50, 100, 500, and 1000. Subtractive pairs like IV and IX shorten repeated marks. This converter maps 1–3999 in both directions in your browser; Easy24 does not receive your input.

Why use this tool

  • Arabic ↔ Roman for 1–3999
  • Live two-way conversion
  • Strict canonical validation
  • Symbol breakdown
  • Clickable Roman chart
  • Unlimited use — no daily cap

Questions

What does Roman Numerals Converter do?

It converts integers between 1 and 3999 into standard Roman numerals and validates Roman input back to Arabic numbers.

Why is IIII rejected?

Standard Roman uses subtractive notation: 4 is IV, not IIII. The tool only accepts the canonical form that matches the usual conversion table.

Why stop at 3999?

Without overlines (vinculum), M repeats up to 3999 (MMMCMXCIX). Larger numbers need special notation not covered here.

Are Unicode Roman characters supported?

Yes. Characters like Ⅻ or Ⅿ are normalized to ASCII I–M before parsing.

Is my input sent to a server?

No. Conversion runs entirely in this tab.

Is there a daily limit?

No. This tool has no daily cap.

Do I need an account?

No. Open the page and use it.

Does it work on a phone?

Yes. It runs in the mobile browser.

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