31 in Roman Numerals
The number 31 is written XXXI in Roman numerals. Click the numeral below to copy it, or use the converter to try any other number.
XXXI uses 2 of the seven Roman numeral symbols and is 4 characters long.
XXXI is purely additive: every symbol is worth what it says and you simply add them together from left to right.
31 in Roman numerals
Also written in words as thirty-one, and read aloud as X X X I.
Roman numeral converter
Convert a number into Roman numerals, or read a Roman numeral back into a number. Works for 1 to 3999, the range the seven standard symbols can express.
How 31 breaks down into Roman numerals
30 + 1 = 31, so XXX + I = XXXI.
| Place value | Roman numeral | Why | Copy |
|---|---|---|---|
| 30 | XXX | X is 10, written 3 times | |
| 1 | I | I is 1 |
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Numbers either side of 31
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Browse the full charts: Roman numerals hub, 1 to 100, years 1900 to 2100.
How to write 31 in Roman numerals, step by step
Roman numerals are built from largest value to smallest. Split 31 into place values first: 30 + 1.
Now swap each part for its symbols: 30 becomes XXX, 1 becomes I. Written together that is XXXI.
No subtraction is needed here, so the symbols are simply added in descending order.
- 30 = XXX (X is 10, written 3 times)
- 1 = I (I is 1)
Is XXXI written correctly?
Yes. XXXI is the standard modern form of 31. A valid Roman numeral never repeats a symbol more than three times in a row, never repeats V, L or D at all, and only ever subtracts I, X or C, and only from the next two larger symbols.
Those rules are what keeps a number to a single accepted spelling, so a reader never has to guess.
How to type XXXI on a keyboard
Roman numerals are ordinary capital letters, so you can type XXXI directly: X, X, X, I. Nothing special is required and it will work in any font, any document and any web form.
Unicode also contains dedicated Roman numeral characters such as Ⅰ, Ⅴ, Ⅹ, Ⅼ, Ⅽ, Ⅾ and Ⅿ. They exist for typesetting East Asian text and they look almost identical, but search engines, spell checkers and screen readers handle the plain letters better, so the letters are usually the right choice.
Where you will see XXXI
Numbers of this size turn up as chapter and page numbers in front matter, as list levels in outlines, as monarch and pope regnal numbers, and in the names of recurring events such as Super Bowl finals.
If you are using XXXI in a document, keep it in capitals. Lowercase roman numerals (xxxi) are conventionally reserved for preliminary page numbering and sub-lists.
Frequently asked questions
How do you write 31 in Roman numerals?
31 is written XXXI. Break it into 30 + 1, then write XXX + I, which joins up as XXXI.
What number is XXXI?
XXXI is 31, or thirty-one in words.
Is there another way to write 31 in Roman numerals?
XXXI is the standard form. Any other arrangement of the same symbols would break the rule that values are written from largest to smallest.
How do I copy XXXI?
Click the large numeral at the top of this page. It copies straight to your clipboard, ready to paste anywhere.
Do Roman numerals have a zero?
No. The system has no symbol for zero and no way to write a negative number or a fraction of one, which is one reason it was replaced for arithmetic.