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Roman Numeral Converter

Convert numbers to Roman numerals and Roman numerals back to numbers.

Input
No upload needed — instant
Privacy
Nothing is uploaded
Cost
Free · no sign-up · no watermark

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Overview

About the Roman Numeral Converter

Convert a whole number to a Roman numeral, or a Roman numeral back to a number, for values from 1 to 3,999, with the symbol-by-symbol breakdown shown.

Roman numerals still turn up on clock faces, book chapters, film credits and monuments. This converter changes whole numbers into Roman numerals and back, for anything from 1 to 3,999, and shows exactly which symbols make up the answer.

The building blocks

I=1  V=5  X=10  L=50  C=100  D=500  M=1000
4=IV  9=IX  40=XL  90=XC  400=CD  900=CM
1994 = M + CM + XC + IV = MCMXCIV

A smaller symbol placed before a larger one subtracts; otherwise symbols add from left to right.

Canonical form only

The converter uses the greedy subtractive rules, so it never produces IIII for 4 or VIIII for 9. When decoding, it round-trips the result — converting the number back to Roman numerals — and rejects anything that does not match, which catches malformed inputs.

Private and instant

Conversions happen in your browser with no upload and no sign-up.

Step by step

How to use the Roman Numeral Converter

  1. Choose the direction — number to Roman, or Roman to number.

  2. Type a whole number from 1 to 3,999, or a Roman numeral.

  3. Read the conversion and the symbol-by-symbol breakdown.

Why use it

Benefits and common use cases

What this tool is good for, and what it deliberately does not try to do.

Both directions

Convert an Arabic number into Roman numerals, or decode a Roman numeral back into a number, from the same tool.

Breakdown included

Each result is split into its symbols and values — MCMXCIV as M(1000) + CM(900) + XC(90) + IV(4) — so you can see how it is built.

Rejects invalid forms

Non-canonical numerals like IIII are refused rather than silently misread, and the answer is verified by converting it back.

Questions

Frequently asked questions

Short, honest answers about quality, limits and privacy.

What are the Roman numeral symbols?

I = 1, V = 5, X = 10, L = 50, C = 100, D = 500 and M = 1000. Numbers are built by combining these, and a smaller symbol before a larger one subtracts, as in IV = 4 and IX = 9.

Why is there no zero?

The Roman system has no symbol for zero and no place value, so it counts from 1. That is why this converter's valid range is 1 to 3,999 — MMM is the largest standard numeral.

How do you write 4 — IIII or IV?

The standard subtractive form is IV, and that is what this tool produces and accepts. IIII appears on some clock faces for symmetry but is not the canonical numeral.