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Roman numeral converter

Turn numbers into Roman numerals and back as you type, with each step shown. Everything is converted on your device.

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Result

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What it does

The Roman numeral converter works both ways:

The answer updates as you type. A breakdown shows the numeral split by place value (MM = 2,000 · XX = 20 · VI = 6), and the sum under it adds the parts up.

How to use it

  1. Under Convert, choose Number to Roman or Roman to number.
  2. Type a whole number from 1 to 3,999, or a Roman numeral such as MMXXVI. Upper or lower case both work.
  3. Select Copy result to put the answer on your clipboard.

The converter remembers the direction you chose and your number on this device. A numeral you type isn’t kept.

How it’s calculated

Each symbol has a value: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1,000. Only IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900) subtract a smaller symbol from a larger one.

To write a number, the converter takes the largest value that fits, again and again, from M, CM, D, CD, C, XC, L, XL, X, IX, V, IV and I. So 2026 is M + M + X + X + V + I = MMXXVI. To read a numeral, it does the same in reverse: MMXXVI = 2,000 + 20 + 6 = 2,026.

Good to know

Privacy

Everything is converted in your browser, on your device. Nothing you type is uploaded. Only your chosen direction and number are kept, in this browser’s storage, so the page can show them again.

Frequently asked questions

How do Roman numerals work?

Seven symbols stand for numbers: I is 1, V is 5, X is 10, L is 50, C is 100, D is 500 and M is 1,000. You write the largest first and add them up, so MMXXVI is 1,000 + 1,000 + 10 + 10 + 5 + 1 = 2,026. A smaller symbol before a larger one is taken away instead, but only in six pairs: IV (4), IX (9), XL (40), XC (90), CD (400) and CM (900).

Why does the converter stop at 3,999?

Standard Roman numerals repeat a symbol at most three times, and M (1,000) is the largest symbol, so MMMCMXCIX (3,999) is the largest number they can write. Larger numbers were once marked with a bar over a numeral, but there's no single agreed form for that.

Is there a Roman numeral for zero?

No. The Romans had no symbol for zero, so the converter starts at 1.

How do I write a year in Roman numerals?

Type the year as the number. 2026 is MMXXVI, 1999 is MCMXCIX and 1066 is MLXVI. The breakdown shows each part, so you can check it on a clock face, a cornerstone or a film's end credits.

Why is IIII not accepted?

IIII is sometimes seen on clock faces, but the standard form of 4 is IV. The converter reads only standard numerals, the same ones it writes, so each number has exactly one numeral.