Switch integers and Roman numerals in either direction

With Roman numerals, students, teachers and analysts can verify a calculation during study or analysis. Switch integers and Roman numerals in either direction.

Switch integers and Roman numerals in either direction. The tool is free in your browser and shows the result without asking you to create an account.

How to use

Enter an integer from 1 to 3999, or paste a sequence of Roman numerals to convert.
Run the conversion to get the matching value in the other system.
Check the result, especially if the input contains unusual marks or lowercase letters.
Copy the converted value for use in an exercise, an analysis, or a document.

Example

The sample contains a common integer. After conversion, look at the Roman form produced and check that it follows subtraction rules, such as IV for four or IX for nine, without giving the result here.

Input

Output

MCMLXXXVII

Limits and formats

The standard conversion covers integers from 1 to 3999; values outside that range are not represented in the usual way.
Roman numerals you enter must follow the expected syntax, or the conversion may fail.
Historical or decorative variants are not necessarily recognized by the tool.
The tool does not perform arithmetic operations on Roman numerals.

Where processing happens

The conversion between integers and Roman numerals happens locally in your browser. The value you enter stays on your device, no request is sent, and the result appears immediately on the page.

Frequently asked questions

Why is the number 4000 not accepted?

The classic Roman notation used here covers integers from 1 to 3999. Beyond that, less common conventions would be needed, such as a bar over a numeral. The tool therefore stays within the range shown in its input field.

Can I write Roman numerals in lowercase?

Some tools accept lowercase, but the standard form uses capital letters. If your input is rejected, change it to uppercase and check that each letter matches a valid Roman value.

Can the result be used for a math calculation?

No, the tool only converts between two notations. To add, subtract, or compare, convert to integers first and do the calculation with Arabic numerals. You can then convert the final answer back if needed.