Roman Numerals to Number

Roman Numerals to Number Converter

Convert Roman numerals to decimal numbers with our fast and accurate online tool. Whether you're a student, a history enthusiast, or a developer, our converter simplifies transforming any standard Roman numeral—like XXV or MCMXC—into its numeric (decimal) equivalent.

What Are Roman Numerals?

Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Unlike the base-10 Arabic numeral system we use today, Roman numerals use a combination of letters from the Latin alphabet: I, V, X, L, C, D, and M.

How Roman Numerals Work

The Roman numeral system is additive and subtractive. For example:

• VI = 6 (5 + 1)
• IV = 4 (5 - 1)

Each numeral has a value, and you calculate the total by adding or subtracting values based on their positions.

Roman Numeral Symbols and Their Values

Symbol	Value
I	1
V	5
X	10
L	50
C	100
D	500
M	1000

How to Convert Roman Numerals to Numbers

To convert a Roman numeral into a number, follow these rules:

1. Start from the left of the Roman numeral.
2. If the current symbol is greater than or equal to the next one, add it to the total.
3. If it's less than the next one, subtract it.

Example:

Input: XXXV  
Result: 35

Conversion Algorithm (Logic/Formula)

Here’s a simplified approach in logical steps:

Let roman = "XXXV"
Start with total = 0
Read from left to right:

X = 10, next X = 10 → 10 added → total = 10  
X = 10, next X = 10 → 10 added → total = 20  
X = 10, next V = 5 → 10 added → total = 30  
V = 5 → last symbol → 5 added → total = 35

Common Roman Numerals and Their Decimal Equivalents

Roman	Number
I	1
V	5
X	10
XXV	25
XL	40
L	50
XC	90
C	100
CD	400
D	500
CM	900
M	1000
MCMXC	1990

Roman Numeral to Decimal Converter Use Cases

This tool is ideal for:

• Educational purposes – teaching or learning Roman numeral concepts
• Developers converting numeral input to integers in code
• Event planners using classical numbering
• Converting ancient document references to modern format

FAQs – Roman to Number Conversion

How do I convert Roman numerals to numbers?

Use the conversion table or the tool above. Roman numerals are read from left to right and combined based on their order and values.

What is XXXV in numbers?

XXXV is 35 in standard decimal notation.

Can I convert large Roman numerals like MCMXC?

Yes, our tool supports values up to 3999, including complex representations like MCMXC (1990).

Is there a Roman numeral for 0?

No. The Roman numeral system does not represent zero.

What are Hindu-Arabic numbers?

Hindu-Arabic numbers are the standard base-10 digits (0–9) used globally today. This tool converts Roman numerals to these digits.

Try It Now

Just type any valid Roman numeral in the input field and hit the "Convert" button. The tool will instantly return the correct decimal value.