Jeans size
A 28-inch waist and 38.5-inch hips make a US 8, EU 40, UK 12 and international S, with the hips setting the size. Enter both tape measurements in inches or centimetres and get a size you can order in any of the four systems. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Waist
- 28
- Hip
- 38.5
- Waist in
- 28 in
- Hip in
- 38.5
- Size
- US 8 / EU 40 / S
- Us
- 8
Jeans size is a pair of tape measurements, not a guess from last year's faded tag or from a dress size that never quite matched the rise. This calculator accepts a positive waist circumference and a positive hip circumference — the two numbers a flexible tape takes at the natural waist and around the fullest part of the seat — and returns the matching jeans size on the US even-number chart together with the equivalent EU numeric size, the UK numeric size, and the international letter from XXS to 3XL. You get a US size you can order, the European and international twins, and a note that says whether the waist or the hip drove the result.
How waist and hip become a matching jeans size
A jeans size is a name for a pair of body circumferences, not a style recommendation and not a conversion from a dress size you already know. The two measurements the industry uses are the waist, taken with a flexible tape at the natural waist or at the height where the intended rise will sit, and the hip, taken around the fullest part of the seat and the upper thighs, keeping the tape level. Those two positive lengths are the only required inputs.
Send them in inches, the default, because US and UK denim tags are still inch-based, or in centimetres with unit set to cm; centimetres are divided by 2.54, the exact international-inch factor, before the chart is read. Each US size from 00 through 28 owns a waist ceiling and a hip ceiling on a conventional women's and unisex denim chart.
The solver finds the smallest row whose waist ceiling is at least the measured waist and whose hip ceiling is at least the measured hip — equivalently, it looks up a size from the waist alone, a size from the hip alone, and keeps the larger of the two so both dimensions actually fit.
That row is the matching jeans size: the US even number shoppers type into a filter, the EU numeric twin from 30 through 60, the UK numeric twin from 4 through 32, and the international letter XXS, XS, S, M, L, XL, XXL, or 3XL. Values well below a 00 or well above a 28 still receive a label rather than a clamp error, because the contract is to fail only when a measurement is not a positive number.
There is no network chart, no brand vanity offset, and no clock. The primary field size is the combined US, EU, and letter label; us, eu, uk, and international travel beside it so a catalogue that prints only one system can be filled without a second conversion.
Where a jeans-size-from-measurements calculator earns its keep
Online denim shops need a waist-and-hip box on the size guide, not a lecture about how a US 8 is sometimes a European 40. A shopper who has just wrapped a tape can type the two numbers and see the matching jeans size before adding a pair to the cart, which cuts the returns that come from guessing between a 6 and an 8. Gift buyers who cannot borrow the recipient's pair can ask for a waist and a hip by text and convert them privately.
Marketplaces that list the same SKU as US 8, EU 40, UK 12, and S can fill those columns from one pair of measurements, so a listing stays consistent when the catalogue is generated rather than typed. Warehouse and uniform teams issuing one-size-per-person kits can turn a short list of tape readings into US, EU, and international sizes without opening a printed wheel.
Keep both measurements positive and finite, pin size, us, eu, and international in your tests, and you get a reproducible jeans size for a product page, a gift checklist, a locker-room intake form, or an edge worker without standing up a fit-lab stack for a two-number lookup. This landing answers a different search from a clothing-size converter that already has a label and only wants another region's number.
What you can do with it
Gift buying without the pair
Convert a waist and hip sent by the recipient into a US jeans size so surprise denim can be ordered without borrowing an existing pair.
Marketplace listings and kit issue
Fill US 8, EU 40, UK 12 and S from one pair of tape readings, or turn a locker-room list of measurements into consistent denim sizes.
FAQ
How do I find my jeans size from waist and hip?
Send positive finite waist and hip circumferences (inches by default, or centimetres with unit set to cm).
Should I measure in inches or centimetres?
Either. Omit unit or send in for inches; send cm for centimetres. Centimetres are divided by 2.54 before the chart is read. Use the same unit for both measurements.
What if my waist and hip suggest different sizes?
If the hip drives a larger size, order that size or look for a curvy / hip-focused cut.
How do US, EU and international jeans sizes relate?
Each chart row is one US even size from 00 to 28, paired with EU 30–60, UK 4–32, and a letter from XXS to 3XL. A typical 28-inch waist and 38.5-inch hip maps to US 8, EU 40, UK 12, and S.
How do I measure my waist and hips for jeans?
Measure the waist at the end of the day, standing relaxed, in the clothes you will wear under the jeans, with the tape snug and level. Measure the hips around the fullest part of the seat without letting the tape drop at the back.
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/life/jeans-size \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"waist":28,"hip":38.5}'const res = await fetch("https://api.kit.forhosting.com/life/jeans-size", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"waist": 28,
"hip": 38.5
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/life/jeans-size",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"waist": 28,
"hip": 38.5
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/life/jeans-size", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"waist":28,"hip":38.5}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"waist":28,"hip":38.5}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/life/jeans-size", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"waist": 28,
"hip": 38.5
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "life.jeans_size",
"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
Zero, negative, missing, or non-finite values fail with invalid_input and are not billed.
How waist and hip become a matching jeans size
Beside those labels the solver also returns waist_numeric, the nearest even inch that men's and unisex denim prints as the waist on a 32x32 tag. driving_fit tells you which tape reading forced the size: waist, hip, or both.
How to measure, what to send, and how errors are reported
Measure the waist at the end of the day in the clothes you will wear under the jeans, standing relaxed, tape snug but not tight, parallel to the floor. Measure the hips around the fullest part of the seat, usually twenty to twenty-three centimetres below the waist, again keeping the tape level; do not let it drop in the back. If you sit a lot or prefer a looser seat, add a little ease to the hip before you send it. POST a JSON body with two required fields, waist and hip, each a positive finite number, and an optional unit that is either in or cm (inches when omitted). The solver also accepts the alias waist_in for the waist, and hips, hip_in, and hip_circumference for the hip, and it reports errors against the canonical names so a form can mark the right control. On success the body echoes the cleaned waist, hip, and unit, returns waist_in and hip_in so a centimetre caller can see the inch values the chart used, puts the matching jeans size in size, and fills us, eu, uk, and international from the same row. waist_numeric is the even-inch denim waist; driving_fit is waist, hip, or both; a formula string restates the smallest-fitting-row rule. Missing fields, empty strings, non-numeric tokens, NaN, Infinity, zero, and negative values all fail with invalid_input and a message that says the named measurement must be a positive number; those failures are not billed. A typical adult pair of 28 inches at the waist and 38.5 inches at the hip returns US 8, EU 40, UK 12, and S, with driving_fit set to hip because 38.5 sits above the US 6 hip ceiling. Successful API calls use the published base of $0.002 per item; the free browser path runs the same solve function without consuming prepaid balance.
Integration use cases
Product-page size guides
Let a shopper type waist and hip and show the matching US, EU and international jeans size before checkout, using the same labels the catalogue API stores.
Technical questions
What does the jeans size calculator cost?
The browser tool is free. API requests use prepaid balance at $0.002 per successful call; invalid input is not billed.