Ordinal Number Converter
Turn any whole number into its ordinal form (1 → 1st) and spell it out in words (first, twenty-first) — free, instant and processed entirely in your browser.
Whole numbers from 0 up to 36 digits (999 decillion). Commas and spaces are ignored.
How to use the Ordinal Number Converter
- Type a whole number. Enter any non-negative integer, from 0 to numbers with up to 36 digits — commas and spaces are fine.
- Read the three forms. The converter instantly shows the ordinal numeral (21st), the ordinal spelled out (twenty-first) and the cardinal spelled out (twenty-one).
- Copy what you need. Each output has its own copy button, ready to paste into invitations, essays, contracts or dates.
About this tool
Ordinal numbers express position or rank — 1st place, the 2nd floor, the 21st century — while cardinal numbers express quantity. English suffixes follow a simple but easily fumbled rule: numbers ending in 1 take "st", in 2 take "nd", in 3 take "rd", and everything else takes "th", except that 11, 12 and 13 always take "th" (so 111th, not 111st). This converter applies the rule correctly for any whole number and also spells the result out in words, handling the irregular forms like first, second, third, fifth, ninth, twelfth and twentieth automatically.
It is useful for writing dates and anniversaries, wedding and birthday invitations, legal documents, race results and academic writing, or for checking English homework. Words follow American convention (no "and", as in "one hundred first") and everything is generated locally in your browser — nothing you type is sent to a server. Need the plain spelled-out number instead? Try the Number to Words tool.
Frequently asked questions
Why is it 11th and not 11st?
Numbers ending in 11, 12 or 13 always take "th" — 11th, 12th, 13th, 111th, 212th — because they are pronounced eleventh, twelfth and thirteenth. Only numbers whose last digit is 1, 2 or 3 outside those cases take st, nd or rd: 21st, 22nd, 23rd.
Does the converter handle negative numbers or decimals?
No — ordinals describe positions in a sequence, so they are only defined for whole numbers: 0 (zeroth), 1, 2, 3 and so on. If you enter a negative number or a decimal, the tool explains why it cannot be converted.
How are large numbers spelled out?
The converter uses the short scale common in modern English: thousand, million, billion (10^9), trillion, and on up to decillion (10^33). For example 1,000,000 becomes "one millionth" as an ordinal and "one million" as a cardinal.
Should I write "twenty-first" with a hyphen?
Yes. Standard English hyphenates compound numbers from twenty-one to ninety-nine, and the same applies to their ordinals: twenty-first, forty-second, ninety-ninth. The converter inserts these hyphens for you.