Roman Numeral Converter
Convert Arabic numbers to Roman numerals and back
Make number conversion quick and fun. This roman numeral converter helps you turn Arabic numbers into Roman numerals, or Roman numerals back into Arabic numbers, in just a few clicks. Enter a value, convert it, and explore the classic charm of Roman notation.
How does the roman numeral converter work?
To use the roman numeral converter, type the number you want to convert into the input box, either as an Arabic number or a Roman numeral. Click “Convert” and you will see the result instantly.
Want to try another value? Click “Reset” to clear the tool and start again.
Did you know?
No zero
Roman numerals do not have a symbol for zero, which limited their use for advanced mathematics compared with the Arabic numeral system.
Largest common number
The largest number typically written using standard Roman numerals is MMMCMXCIX (3999), due to practical limits of the system.
Symbol variations
Early Roman numerals varied, and some symbols may come from older letter forms. For example, C (100) and M (1000) evolved over time.
How to convert Arabic numbers to Roman numerals
Converting Arabic numbers to Roman numerals may look ancient at first, but once you know the rules it is straightforward. This section explains the basics and gives a clear example you can follow.
Basics
The Roman numeral system uses these letters: I, V, X, L, C, D, and M. Each letter has a fixed value, and different numbers are formed by combining them.
- I = 1
- V = 5
- X = 10
- L = 50
- C = 100
- D = 500
- M = 1000
Key rules
- Repetition adds value: You can repeat a numeral up to three times to add its value. For example, III means 3.
- Larger before smaller adds: If a smaller numeral comes after a larger one, you add them. For example, VI is 5 + 1 = 6.
- Smaller before larger subtracts: If a smaller numeral comes before a larger one, you subtract it. For example, IV is 5 minus 1 = 4.
- Limited repetition: V, L, and D are not repeated, unlike I, X, C, and M. For example, V is valid, but VV is not.
Example: Convert 39 to Roman numerals
Let’s convert 39 step by step.
30 is XXX (10 + 10 + 10).
9 is IX (10 minus 1).
Put them together: 39 is XXXIX.
Now you can convert Arabic numbers into Roman numerals with confidence. Use it for dates, chapter numbers, clocks, and anything else that looks better in Roman numerals.
How to write Roman numerals for 4000 or more
Standard Roman numerals comfortably cover numbers up to 3999, such as MMMCMXCIX. For larger numbers, an overline is used to multiply a numeral by 1,000.
Overline as a multiplier
Adding a horizontal line above a numeral means its value is multiplied by 1,000.
How it works in practice
For example, 4000 is written as I̅V̅, meaning 4 times 1,000. Likewise, 5000 is V̅, meaning 5 times 1,000.
Building bigger numbers
To write 6000, you combine V̅ (5000) and M (1000) to get V̅M.
Example: 7400
7000 is V̅I̅I̅ (7 times 1,000), then add 400 as CD. Together, 7400 is V̅I̅I̅CD.