Roman Numerals is a free math & calculators tool that runs entirely in your browser — arabic ↔ Roman, up to 3999999. No upload, no account, no limits.
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How to use Roman Numerals
Open the Roman Numerals tool.
Paste or type your number into the input field.
The output updates as you type — adjust the options if you need a different format.
Copy the result, or share the URL to hand the exact input to someone else.
About Roman Numerals
Convert Arabic numbers to Roman numerals and back, both directions at once. Overlined letters extend the range far past the usual limit, supporting values up to 3,999,999.
What people use it for
Write a year or chapter number in Roman numerals.
Decode a Roman numeral into a regular number.
Frequently asked questions
How high can it go?
Up to 3,999,999 using overline notation (e.g. V̅ = 5000) for the thousands.
Is it private?
Every calculation happens on this page, in your own browser. Your input is never sent to a server, never logged and never used for training — which also means the tool keeps working when you are offline.