Ordinal words converter
21 becomes twenty-first, with 21st alongside when space is tight. Only the last word turns into a rank, so one hundred one reads one hundred first, never oneth hundredth. Made for certificates, rankings, lessons and speech prompts. Free in your browser.
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Worked example
- N
- 21
- Words
- twenty-first
- Short
- 21st
- Suffix
- st
- Language
- en
Ordinals name position, rank, and sequence: first place, twenty-first birthday, one hundredth anniversary, the third item in a list. Writers, teachers, accessibility layers, and document templates often need those ranks in full English words rather than bare digits or abbreviated 1st and 2nd labels alone. This capability takes a plain integer and returns a deterministic American English ordinal spelling—twenty-first for twenty-one, first for one, zeroth for zero—so homework checkers, ranking UIs, certificates, and speech prompts share one stable contract. Non-integer input fails with a clear invalid input error instead of a guessed wording.
What English ordinal spelling returns and which inputs are valid
American English ordinal spelling starts from the same short-scale place values used for cardinal numbers—thousand, million, billion, and so on—then changes only the final word so the phrase names a rank rather than a quantity. One becomes first, two becomes second, three becomes third, five becomes fifth, twelve becomes twelfth, and round tens such as twenty become twentieth. Compound forms keep a hyphen on the tens unit: twenty-one becomes twenty-first, forty-two becomes forty-second, and ninety-nine becomes ninety-ninth.
When the integer ends in a round hundred, thousand, or million, the scale word itself takes the ordinal ending: one hundredth, two thousandth, three millionth. Optional leading plus or minus signs mark positive or negative ranks; the engine prefixes negative for signed results. Common thousands separators such as commas or spaces in clear groupings like one comma two three four are stripped when the value remains a whole integer.
Reading words, short form, suffix, and how compound ordinals are built
The short field pairs the absolute digits with the conventional English suffix so user interfaces can show 21st beside twenty-first when space is tight. The suffix field alone is st, nd, rd, or th, including the eleven through thirteen exceptions that stay th even though they end in one, two, or three. Only the last word of the cardinal phrase is ordinalized: one hundred twenty-first keeps hundred in cardinal form and changes first; two thousand third changes only third.
That rule matches natural English and avoids incorrect chains such as oneth hundredth. Quick checks build trust: one becomes first; two becomes second; three becomes third; four becomes fourth; eleven becomes eleventh; twelve becomes twelfth; twenty becomes twentieth; twenty-one becomes twenty-first; one hundred becomes one hundredth; one hundred one becomes one hundred first; zero becomes zeroth.
What you can do with it
Certificates, awards, and anniversary copy
Event and HR templates spell ranks and milestone years in full English ordinals (twenty-first, one hundredth) next to numeric labels for print and digital certificates.
Leaderboards and ranking UIs
Sports, contest, and product dashboards convert place numbers into first, second, and twenty-third for accessible labels, announcements, and export reports.
FAQ
How do I convert 21 to twenty-first?
The response words field is twenty-first; short is 21st.
How are 1st, 2nd, 3rd, and 11th handled?
words uses first, second, third, eleventh. short uses 1st, 2nd, 3rd, 11th. The eleven–thirteen group correctly keeps the th suffix in the short form.
Is the ordinal words converter free?
The browser tool runs free on your device.
Is this the same as spelling a number in English words?
No. Cardinal spelling (one thousand two hundred thirty-four) is a different intent. Use this tool for ordinals (ranks and positions) such as twenty-first.
Which word changes in a long number?
Only the last one. One hundred twenty-one becomes one hundred twenty-first, and two thousand three becomes two thousand third, so you never get broken forms such as oneth hundredth.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/fmt/spell-ordinal \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"n":21}'const res = await fetch("https://api.kit.forhosting.com/fmt/spell-ordinal", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"n": 21
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/fmt/spell-ordinal",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"n": 21
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/fmt/spell-ordinal", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"n":21}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"n":21}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/fmt/spell-ordinal", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"n": 21
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "fmt.spell_ordinal",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
What English ordinal spelling returns and which inputs are valid
Send the required field n as a JSON integer or as an integer string; aliases value, number, input, and num are accepted when your form or SDK already uses those labels. Empty strings, bare letters, decimal points, fractional values, and scientific notation strings are rejected with invalid_input because this product promises an exact ordinal for a well-formed integer, not a fuzzy interpretation of free text or a decimal rank. Magnitudes stay inside a safe integer range for Worker isolate safety while still covering classroom exercises, sports standings, anniversary numbers, and ordinary business sequence labels.
Reading words, short form, suffix, and how compound ordinals are built
On success the response echoes the integer in the field n and returns words as the full American English ordinal ready for display, speech synthesis, certificates, or document templates. Boolean is_negative summarizes signed input without forcing callers to reparse the string. language is always en and style is always american_short_scale so localization layers can branch when other languages ship as separate capabilities. method is always spell_ordinal for telemetry and algorithm labeling. Missing n, non-integer numbers, decimal strings, empty strings, overlong magnitudes, and scientific strings all fail with invalid_input and are not charged after validation rejects the request.
API usage, pricing, ranking workflows, and practical limits
Call the free in-browser ordinal words converter for homework checks, lecture demos, certificate previews, and quick editorial verification without installing a linguistics library or writing a throwaway script. Prefer classroom-scale and business-scale integers for production traffic, and keep magnitudes inside the published safe range for isolate safety. Authors shipping SDKs can map words into a primary answer box while short and suffix feed compact badges and table columns—the same split humans use when they write twenty-first in prose and 21st in a tight header. Send a JSON body with the required n field, or use the documented aliases when your client already labels the rank as value or number. Use the prepaid API when a ranking dashboard, awards generator, tutoring platform, voice prompt builder, content pipeline, or document renderer needs a stable English ordinal contract under KIT balance at $0.002 per successful item; validation failures never consume balance. Pair this endpoint with the cardinal spell-number tool when a product must show both quantity words and rank words side by side, or with PDF and mail tools when the next step is embedding the ordinal line into a customer-facing document.
Integration use cases
Homework, tutoring, and auto-graders
Students and platforms check that 21 is twenty-first and that decimals or free text fail with a clear invalid_input error instead of a wrong spelling.
Technical questions
What happens if I send a decimal like 21.5?
The request fails with invalid_input. This capability spells ordinals for integers only; non-integer input is rejected and not charged.