Roman Numeral Converter

What is roman numeral converter?

Roman numerals still appear on clocks, book chapters, movie sequels, building cornerstones and the Super Bowl. Reading them is easy once you know the rules, but long numerals such as MCMXCIV are easy to get wrong.

This tool converts in both directions. It also checks that a numeral is written in standard form, so a typo is caught instead of silently accepted.

How to use the roman numeral converter

1. Type a number from 1 to 3999, or a Roman numeral.
2. The result appears as you type.
3. Use the table of symbols below if you want to check the logic.

How the roman numeral converter works

Values are written from largest to smallest and added. When a smaller symbol comes before a larger one, it is subtracted, as in IV for 4 and CM for 900. Numerals are built from thousands, hundreds, tens and ones.

Worked example

Common uses of the roman numeral converter

• Reading the year on a film credit, monument or building.
• Numbering chapters, outlines, events such as the Super Bowl and monarchs.
• Checking a clock face or watch dial.
• Doing school homework on number systems.
• Choosing tattoo or jewelry designs with dates.

Tips and common mistakes

Never repeat a symbol more than three times in a row. 4 is IV, not IIII, in standard writing.

Standard Roman numerals have no zero and cannot reach 4000 without extra marks.

Background: what to know before you rely on it

Roman numerals grew from tally marks used in ancient Italy and were the main number system across the Roman Empire and medieval Europe. They have no zero and no place value, which made arithmetic slow and helped Hindu Arabic numerals take over in the Middle Ages. Subtractive forms such as IV and IX became standard later. Older inscriptions sometimes show IIII for 4, and many clock makers still use it for visual balance. Today Roman numerals survive in formal and decorative uses. Remember the rule of three: a symbol can repeat up to three times, and only I, X and C can be used for subtraction.

Private, free and fast

This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all converters, or browse the full list of tools.

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Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. Check critical conversions with an official source.