What is the rule for 1st, 2nd, 3rd and 4th?

The suffix follows the last digit: 1 takes st (first), 2 takes nd (second), 3 takes rd (third), and everything from 4 to 9 plus 0 takes th. So 1st, 2nd, 3rd, 4th, 5th, then 6th, 7th, 8th, 9th. This holds for any number ending in those digits once you clear the 11 to 13 exception, which is why 21 is 21st, 32 is 32nd and 43 is 43rd.

Why are 11th, 12th and 13th all th and not 11st, 12nd, 13rd?

Because the suffix is chosen by the last TWO digits when they land in the 11 to 13 range. Eleventh, twelfth and thirteenth historically end in th, so the tool checks for 11, 12, 13 first and only then falls back to the last single digit. That is why 111 is 111th and 213 is 213th, while 121 ends the run and goes back to 121st.

How does 21st work, and what about 22nd and 23rd?

Once you are past 13 the last digit takes over again. 21 ends in 1 so it is 21st, 22 ends in 2 so it is 22nd, 23 ends in 3 so it is 23rd, and 24 through 29 all take th. The same pattern repeats every ten: 31st, 42nd, 53rd, 64th. Only the 11 to 13 band inside each hundred breaks it, so 211th, 212th, 213th, then 221st.

How do I get the spelled-out ordinal word like twenty-first?

Switch your eye to the ordinal words row. The tool spells the cardinal number then turns the final word into its ordinal stem: one becomes first, two becomes second, five becomes fifth, twelve becomes twelfth, and twenty becomes twentieth. Compound numbers keep the hyphen and only ordinalise the tail, so 21 reads twenty-first, 42 reads forty-second, and 100 reads one hundredth.

What about the Chinese ordinal form 第N?

Chinese marks ordinals with the prefix 第 before the number. Small values read as numerals, 第一 for first, 第二 for second, 第十 for tenth, while larger ones keep the Arabic digit the way people actually write them, 第21 and 第100. The tool also shows a fully spelled-out variant, 第二十一 and 第一百, for formal text where numerals are written out.

Does it handle 0, negative numbers and big numbers?

Yes. Zero gives 0th and zeroth, a negative keeps its sign so -3 is -3rd and negative third, and large numbers spell out up to the quintillion range, for example 1000 is 1000th and one thousandth. Decimals and fractions are not ordinals, so those rows stay blank rather than guessing at a meaning that does not exist.

Writing dates and rankings in copy

A content writer drafting an event recap needs the 1st, 2nd and 3rd place finishers and the 21st of the month spelled consistently. Paste the placement numbers, read off the correct suffix for each, and never ship a 21th or a 22rd in published copy again.

Teaching the ordinal rule to students

An English teacher explaining why 11th breaks the pattern can show the side-by-side suffix and the spelled-out word together. Type 11, 12, 13 to demonstrate the exception, then 21, 22, 23 to show the rule resuming, all on one screen with the words underneath.

Generating ordinal labels for a list or schedule

Building a numbered agenda or a leaderboard, you need first, second, third all the way down. Drop the whole column into batch mode, copy the ordinal words out, and paste them straight into your spreadsheet or slide deck without hand-typing each suffix.

Localising an interface into Chinese

A product going bilingual needs ranking labels in both English ordinals and the Chinese 第N form. The batch table gives you 1st and 第一 on the same row, so you can fill both locale columns from a single export instead of reconciling two separate lists.

Ordinal Number Converter

Cardinal to ordinal both ways: 1st 2nd 3rd suffixes, twenty-first words, plus Chinese 第N, single or batch, copy ready

Runs locally
Category Format Converter
Best for Turning pasted content or local files into a handoff-friendly format.

Number

Examples

Ordinal21st

Suffixst

Ordinal wordstwenty-first

Chinese第21

Chinese (spelled)第二十一

What this tool does

Turn any whole number into its ordinal form three ways at once, with the 11/12/13 rule handled correctly. Type 1 and get 1st, type 2 and get 2nd, type 3 and get 3rd, then 4th, but 11th, 12th and 13th all keep the th suffix because the ending is decided by the last two digits, not the last one. So 21 becomes 21st, 22 becomes 22nd, 111 becomes 111th and 121 jumps back to 121st. Alongside the suffix abbreviation you get the spelled-out English ordinal word, first, twenty-first, one hundredth, and the everyday Chinese form 第一, 第二, 第21. Paste a whole column of numbers, one per line, and the batch table converts every row at once with one-click copy. Everything runs in your browser as plain JavaScript, no upload, and the shareable link reopens on the same number.

Tool details

Input: Text + Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Format Converter · Student; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Ordinal Number Converter fits into your work

Use it when the main problem is getting content from one practical format into another.

Conversion jobs

Turning pasted content or local files into a handoff-friendly format.
Previewing a conversion before you use it in a larger workflow.
Cleaning small format mismatches without opening a full editor.

Conversion checks

Try a small sample first when the source format is messy.
Check character encoding, separators, and line endings after conversion.
Keep the source until the converted output has been reviewed.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Writing dates and rankings in copy
A content writer drafting an event recap needs the 1st, 2nd and 3rd place finishers and the 21st of the month spelled consistently. Paste the placement numbers, read off the correct suffix for each, and never ship a 21th or a 22rd in published copy again.
Teaching the ordinal rule to students
An English teacher explaining why 11th breaks the pattern can show the side-by-side suffix and the spelled-out word together. Type 11, 12, 13 to demonstrate the exception, then 21, 22, 23 to show the rule resuming, all on one screen with the words underneath.
Generating ordinal labels for a list or schedule
Building a numbered agenda or a leaderboard, you need first, second, third all the way down. Drop the whole column into batch mode, copy the ordinal words out, and paste them straight into your spreadsheet or slide deck without hand-typing each suffix.
Localising an interface into Chinese
A product going bilingual needs ranking labels in both English ordinals and the Chinese 第N form. The batch table gives you 1st and 第一 on the same row, so you can fill both locale columns from a single export instead of reconciling two separate lists.

Common pitfalls

Writing 11st, 12nd or 13rd. The 11 to 13 band always takes th, so it is 11th, 12th, 13th. The single-digit rule only applies after you have ruled out that band.
Assuming the suffix follows the first digit instead of the last. It is the ending that matters, 113 is 113th and not 113rd, because 13 falls in the th band even though it starts with a 1.
Adding a suffix to a decimal or fraction. Ordinals describe position in a sequence, so 2.5th is meaningless. Use whole numbers only and leave fractional values to a regular number.

Privacy

Every conversion runs as plain JavaScript inside your browser tab. The number you type, the batch list you paste, and all three ordinal forms stay on the page and are never uploaded or logged. The one thing to know: the shareable link encodes your input in the query string, so a link pasted into chat records that number in the recipient server access log. For anything sensitive, use the copy button and paste the text instead of sharing the URL.

FAQ

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Ordinal Number Converter

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Ordinal Number Converter fits into your work

Conversion jobs

Conversion checks

Good next steps

Real-world use cases

Writing dates and rankings in copy

Teaching the ordinal rule to students

Generating ordinal labels for a list or schedule

Localising an interface into Chinese

Common pitfalls

Privacy

FAQ

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