How to Use the Roman Numerals Converter
Type a number (1–3999) to see the Roman numeral, or type a Roman numeral to see the integer. Conversion is live as you type.
Roman Numerals Converter Formula
Greedy algorithm: subtract largest Roman value that fits; M=1000, CM=900, D=500…Example Calculation
Convert 2024 to Roman:
MM + XXIV = 1000+1000+10+10+4
MMXXIV
The Seven Symbols
Roman numerals are built from just seven letters, each with a fixed value. Once you know them, you can read or write any number up to 3,999.
- I = 1
- V = 5
- X = 10
- L = 50
- C = 100
- D = 500
- M = 1,000
Numbers are formed by combining these symbols and adding their values from left to right — except in the specific subtraction cases described below.
The Rule That Trips Everyone Up: Subtraction
Roman numerals are mostly additive — VI is 5 + 1 = 6. But to avoid four identical symbols in a row, a smaller symbol placed before a larger one is subtracted. So IV is 5 − 1 = 4 (not IIII), and IX is 10 − 1 = 9. This subtractive rule applies only to specific pairs: I before V or X, X before L or C, and C before D or M. You will never see, for example, IL for 49 — it is written XLIX (10 less than 50, then 10 less than 10). Getting the subtraction pairs right is the whole skill.
Worked Examples
Seeing how numbers break down makes the system click. Each is built by writing the largest values first and applying subtraction where needed.
- 40 = XL (10 before 50)
- 90 = XC (10 before 100)
- 140 = CXL (100 + 40, i.e. C + XL)
- 400 = CD (100 before 500)
- 2026 = MMXXVI (1000 + 1000 + 10 + 10 + 5 + 1)
- 3999 = MMMCMXCIX, the largest standard Roman numeral
To convert any number yourself, break it into thousands, hundreds, tens, and units, convert each part separately, then write them in order. The converter above does this instantly in both directions — number to numeral and numeral back to number.
Why We Still Use Them
Roman numerals survive in plenty of modern places: clock faces, book chapters and prefaces, movie sequels and copyright years, the Super Bowl, monarchs and popes (Elizabeth II, Louis XIV), and the names of events like the Olympic Games. They have no zero and no place value, which makes arithmetic with them clumsy — one reason the world adopted the Hindu-Arabic numerals we use for calculation. But for numbering, naming, and adding a touch of formality, they remain firmly in use, which is why being able to read and write them is still a genuinely useful skill.
Frequently Asked Questions
What is the largest Roman numeral?
Standard Roman numerals go up to 3,999 (MMMCMXCIX). There is no standard representation for 4,000+ in classical Roman numerals, though extended systems exist.