Roman Numeral Converter

Our Roman Numeral Converter will let you convert a whole number to a number from the Roman Numeral System.

Roman numerals look like mysterious codes, but they are pretty straightforward once you learn them! As you might guess, roman numerals originated in ancient Rome (around 900 to 800 B.C.). The Romans needed a counting system that helped make communications easier. In other words, they were tired of counting on their fingers.

The Roman Numeral system played a big role in civilization, but it was not without its faults. There is no zero and there’s no way of working with fractions. Soon, the Romans realized that the system made things more challenging.

Despite civilization moving on from Roman numerals, we still find ways to slip them in here and there. That’s why we made our roman numeral converter—to help you understand a little bit of the past! 

How to Use the Roman Numeral Converter

Our Roman Numeral Converter is extremely simple to use. There are only three parts: 

  • A box on top where you enter the number you want to convert
  • The CONVERT button
  • The START OVER button

To convert any standard number to a Roman numeral:

  1. Type any number from 1 to 3,999,999 into the box. 
  2. Click CONVERT.
  3. Write down your answer. 
  4. Click START OVER to convert another number. 

That’s all there is to it! Easy, right?

Enter a whole number from 1 to 3,999,999

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Seven Symbols of the Roman Numeral System

To help you understand how to work with roman numerals—not just convert them—we’ve put together a handy guide. It all starts with seven letters and their modern equivalent values.

Symbol Value

I 1

V 5

X 10

L 50

C 100

D 500

M 1,000

How to Read and Write Roman Numerals 

We write Roman numerals in either single letters or as a combination of two or more. These letters always follow a left-to-right arrangement, and their position determines whether you have to add or subtract the values to get the roman numeral you are writing or reading. Sounds confusing, but trust us—it’ll get much easier. 

There are four main rules to remember when working with Roman numerals.

Rule One

Add the numerals together if your starting symbol is greater than the symbols that come after it. For example: 

  • XII is 12 because X (10) is higher than I (1). 
    • X+I+I = 12.

Rule Two

Subtract the numerals if your starting symbol is lower than the symbol that comes after it. For example: 

  • CD is 400 because C (100) is lower than D (500).
    • D-C = 400.

There are some other important rules of subtraction you should keep in mind.

  • You can only subtract I, X, or C (powers of 10) from other numerals, but not V or L. 
    • IX is 9, but 95 is XCV, not VC. 
    • CD is 400, but 950 is CML, not LM.
  • You may only subtract one number from another number. 
    • 47 is XLVII, not IIIL.
    • 98 is XCVIII, not IIC.
  • You cannot subtract a numeral from another numeral if that other numeral is more than 10 times bigger. That’s a mouthful, we know, so here are some examples.
    • You can subtract 1 from 10 to make IX. However, but you cannot subtract X from M to make 990, which is correctly notated as CMXC.
    • You can subtract 10 from 50 to make XL or 40. However, you cannot subtract V from D to make 495, which is correctly notated as CDXCV.

Rule Three

Add an overbar ( ¯¯¯ ), also known as a vinculum, on top of the symbol or symbols to multiply the number’s value by 1,000. XLVII with an overbar would be 47,000.

Rule Four

You can only repeat symbols up to three times.

  • 20 is XX but 40 is XL.
  • 300 is CCC but 400 is CD. 

Though we don’t use Roman numerals often, we’ll still see them inside of books, during football season, and even as fancy labels. So if you need a translation, remember, we are just a website away!