Ring Size Converter API

GET

Translate international ring sizes instantly at checkout.

Ring Size Converter translates international ring sizes or millimeter diameters into US and UK standards, inside diameter, and circumference. Paid plans add equivalent sizes for Europe, Japan, Switzerland, and Australia.

Try it — live request, no key required

Request

GETapi.apiverve.com/v1/ringsizeconverter?size=7&from=us

Query parameters

sizestring

fromstring

Verification

Format

No key required to try it. Get a key to use it in your app.

Example

{
  "status": "ok",
  "error": null,
  "data": {
    "input_diameter_mm": 17.3,
    "circumference_mm": 54.3,
    "conversions": {
      "diameter_mm": 17.3,
      "circumference_mm": 54.3,
      "us": 7,
      "uk": "N",
      "eu": 52,
      "jp": 17,
      "ch": -22,
      "au": "N"
    },
    "note": "Sizes are approximate. For accurate sizing, visit a jeweler."
  }
}

About the Ring Size Converter API

Ring Size Converter works by converting input sizes to diameter measurements, then calculating equivalent sizes in all supported regions. Can accept either standardized sizes or direct diameter measurements for maximum flexibility.

What people use it for

Jewelry E-commerce: Help customers find their ring size when purchasing from international jewelers and retailers
Gift Shopping: Convert ring sizes when buying jewelry gifts for people in different countries
Jewelry Sizing: Provide sizing tools for jewelers working with international customers and standards
Size Guides: Create comprehensive ring size conversion charts for jewelry product listings

Ways to call it

One endpoint, many ways in — REST with JSON, XML, YAML and CSV, plus GraphQL and an MCP interface for AI agents.

JSON: Default REST response
XML: Markup format
YAML: Human-readable
CSV: Tabular export
GraphQL: Query language
MCP: For AI agents

View all integrations →

Other ways to use Ring Size Converter

Same data, same APIVerve account, same credit balance — one key works on all of them.

Give it to an AI agentConnect over MCP and your agent calls it as a native tool — Claude, Cursor, ChatGPT.on VerveKit Google Sheets or ExcelA =VERVE() formula fills a column — no script, no export, recalculates in place.on VerveSheets Ground an agent on itA cited, machine-checkable fact your model can't produce on its own.on VerveContext

Questions.

Common questions about the Ring Size Converter API.

Read the docs →

Which international ring size systems are supported?

US and UK conversions work on every plan; EU, JP, CH, and AU standards require a paid plan. You can also supply a raw inside diameter measurement in millimeters to calculate sizes across US and UK on every plan, or across all of these regions at once on paid plans.

Can I convert from raw finger or ring measurements?

Yes. If a shopper only knows their inside diameter in millimeters, the diameter endpoint converts that measurement directly into equivalent standard sizes and inside circumference values across US and UK on every plan, and across all regions on paid plans.

Are European, Japanese, Swiss, and Australian sizes included on the Free plan?

No. The Free plan only returns US and UK conversions. Conversions for EU, Japan, Switzerland, and Australia require any paid subscription starting with the Starter plan.

Is it cheap enough to convert ring sizes for every shopper on my store?

Yes. Each lookup costs 2 credits, which works out to about $0.0003 per call or $0.30 per 1,000 conversions on the Starter plan. You also receive 100 free conversions every month to test the integration.

Can I use these conversions in a commercial jewelry store?

Yes, provided you are on a paid plan. Commercial use requires a paid subscription starting with Starter, and you may display the converted sizing data directly inside your storefront or sizing guide.

Request parameters — GET /v1/ringsizeconverter

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them. Anything not listed here is dropped rather than passed through.

Required

Parameter	Type	Example	Description
`size`Required	string	`7`	The ring size to convert
`from`Required	string	`us`	Source region `usukeujpchau`

Example request

1
2

curl "https://api.apiverve.com/v1/ringsizeconverter?size=7&from=us" \
  -H "x-api-key: YOUR_API_KEY"

Authentication

Send your key in the x-api-key header. That is the only auth step — no token exchange, and no per-endpoint scope to configure.

Header	When	Value
`x-api-key`Required	Every request	Your API key. Header names are case-insensitive, so `X-API-Key` is the same header.
`Authorization`Alternate	Instead of the above	`Bearer <key>` — for clients that only expose bearer auth. Resolves to the same account and the same billing.

401 is the only auth verdict

A 401 means the key is missing, invalid or expired. A 403 means the key is valid but not permitted here — blocked by a key restriction or an IP allow-list. Running out of credits is a 429.

Response — GET /v1/ringsizeconverter

Every APIVerve endpoint returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape.

Sample response

{
  "status": "ok",
  "error": null,
  "data": {
    "input_diameter_mm": 17.3,
    "circumference_mm": 54.3,
    "conversions": {
      "diameter_mm": 17.3,
      "circumference_mm": 54.3,
      "us": 7,
      "uk": "N",
      "eu": 52,
      "jp": 17,
      "ch": -22,
      "au": "N"
    },
    "note": "Sizes are approximate. For accurate sizing, visit a jeweler."
  }
}

Response fields

Paths are relative to data. Premium fields are absent rather than zeroed on plans that do not include them, so check for presence instead of comparing to 0.

Field	Type	Example	Description
`input_diameter_mm`	number	`17.3`	Ring diameter in millimeters
`circumference_mm`	number	`54.3`	Inside circumference of the ring in millimetres
`conversions`	object	`{...}`	The equivalent size in every supported sizing system
`diameter_mm`	number	`17.3`	Inside diameter in millimetres
`circumference_mm`	number	`54.3`	Inside circumference in millimetres
`us`	number	`7`	US ring size
`uk`	string	`"N"`	UK ring size
`eu`Premium	number	`52`	EU ring size
`jp`Premium	number	`17`	Japanese ring size
`ch`Premium	number	`-22`	Swiss ring size
`au`Premium	string	`"N"`	Australian ring size
`note`	string	`"Sizes are approximate. For accurate sizing, visit a jeweler."`	Caveat that sizes are approximate and a jeweller should confirm

Response headers

Every response carries your balance, so your own code always knows where it stands without polling anything. All four are exposed to browsers through CORS.

Header	What it carries
`x-api-remaining-credits`	Credits left in the current cycle
`x-api-credits-used`	Credits spent in the current cycle
`x-api-max-credits`	The allowance for the cycle
`x-api-version`	Version of the endpoint that answered

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change.

Status	Meaning	What to do
`400`	Input was rejected	Read `error`; it names the parameter that has to change.
`401`	Key missing or invalid	Check the header name and the key value.
`403`	Key valid, but not permitted here	A key restriction or an IP allow-list — never a bad key.
`429`	Rate limited, or out of credits	Read `error` to tell them apart, then back off or top up.

What a call costs — 2 credits per call

Credits are shared across every APIVerve API — one balance, one key, one bill. Failed requests never count against it, so a rejected input costs nothing.

Plan	Per month	Credits	Ring Size Converter calls	Per 1,000 calls
Free	Free	200	100	Free
Starter	$29.99	200,000	100,000	$0.30
Pro	$99.99	1,000,000	500,000	$0.20
Mega	$299.99	4,000,000	2,000,000	$0.15

Calls are what the credits buy at this API's rate — spend them here, on any of the other APIs, or across both. Nothing is reserved per endpoint.

Compare all pricing tiers →

Call it from cURL — GET /v1/ringsizeconverter

No SDK to install — this is a plain HTTPS call to /v1/ringsizeconverter with your key in the x-api-key header. Swap in a real key and it runs as-is.

cURL

1
2

curl "https://api.apiverve.com/v1/ringsizeconverter" \
  -H "x-api-key: YOUR_API_KEY"

Resources

GitHubapiverve/ringsizeconverter-apiSource, issues and the examples this page is built from.ReferenceRing Size Converter API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

@apiverve/ringsizeconverternpm apiverve-ringsizeconverterPyPI APIVerve.API.RingSizeConverterNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Node.js — GET /v1/ringsizeconverter

Install the Node.js SDK, then call the Ring Size Converter API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.

Install — npm

npm install @apiverve/ringsizeconverter

Node.js

const res = await fetch("https://api.apiverve.com/v1/ringsizeconverter", {
  headers: { "x-api-key": "YOUR_API_KEY" },
});
const { data } = await res.json();
console.log(data);

Resources

npm@apiverve/ringsizeconverterThe published Node.js client, versioned and signed.GitHubapiverve/ringsizeconverter-apiSource, issues and the examples this page is built from.ReferenceRing Size Converter API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

apiverve-ringsizeconverterPyPI APIVerve.API.RingSizeConverterNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Python — GET /v1/ringsizeconverter

Install the Python SDK, then call the Ring Size Converter API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.

Install — PyPI

pip install apiverve-ringsizeconverter

Python

import requests

res = requests.get(
    "https://api.apiverve.com/v1/ringsizeconverter",
    headers={"x-api-key": "YOUR_API_KEY"},
)
print(res.json()["data"])

Resources

PyPIapiverve-ringsizeconverterThe published Python client, versioned and signed.GitHubapiverve/ringsizeconverter-apiSource, issues and the examples this page is built from.ReferenceRing Size Converter API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

@apiverve/ringsizeconverternpm APIVerve.API.RingSizeConverterNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from C# / .NET — GET /v1/ringsizeconverter

Install the C# / .NET SDK, then call the Ring Size Converter API with your key. The client wraps the same HTTPS request, so anything it returns is what the endpoint returns.

Install — NuGet

dotnet add package APIVerve.API.RingSizeConverter

C# / .NET

using var client = new HttpClient();
client.DefaultRequestHeaders.Add("x-api-key", "YOUR_API_KEY");

var json = await client.GetStringAsync("https://api.apiverve.com/v1/ringsizeconverter");
Console.WriteLine(json);

Resources

NuGetAPIVerve.API.RingSizeConverterThe published C# / .NET client, versioned and signed.GitHubapiverve/ringsizeconverter-apiSource, issues and the examples this page is built from.ReferenceRing Size Converter API docsEvery parameter, every response field, and the errors.ParametersWhat this call acceptsRequired and optional inputs, with example values.

Also published for

@apiverve/ringsizeconverternpm apiverve-ringsizeconverterPyPI

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Go — GET /v1/ringsizeconverter

No SDK to install — this is a plain HTTPS call to /v1/ringsizeconverter with your key in the x-api-key header. Swap in a real key and it runs as-is.

req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/ringsizeconverter", nil)
req.Header.Set("x-api-key", "YOUR_API_KEY")

res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))

Resources

Also published for

@apiverve/ringsizeconverternpm apiverve-ringsizeconverterPyPI APIVerve.API.RingSizeConverterNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from PHP — GET /v1/ringsizeconverter

No SDK to install — this is a plain HTTPS call to /v1/ringsizeconverter with your key in the x-api-key header. Swap in a real key and it runs as-is.

PHP

$ch = curl_init("https://api.apiverve.com/v1/ringsizeconverter");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-api-key: YOUR_API_KEY"]);

$response = curl_exec($ch);
echo $response;

Resources

Also published for

@apiverve/ringsizeconverternpm apiverve-ringsizeconverterPyPI APIVerve.API.RingSizeConverterNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

Call it from Ruby — GET /v1/ringsizeconverter

No SDK to install — this is a plain HTTPS call to /v1/ringsizeconverter with your key in the x-api-key header. Swap in a real key and it runs as-is.

Ruby

require "net/http"

uri = URI("https://api.apiverve.com/v1/ringsizeconverter")
req = Net::HTTP::Get.new(uri)
req["x-api-key"] = "YOUR_API_KEY"

res = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) { |h| h.request(req) }
puts res.body

Resources

Also published for

@apiverve/ringsizeconverternpm apiverve-ringsizeconverterPyPI APIVerve.API.RingSizeConverterNuGet

Only the languages APIVerve ships a client for are listed — the rest call the endpoint directly over HTTPS.

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Ring Size Converter API

Try it — live request, no key required

About the Ring Size Converter API

What people use it for

Ways to call it

Other ways to use Ring Size Converter

Questions.

Request parameters — GET /v1/ringsizeconverter

Required

Authentication

Response — GET /v1/ringsizeconverter

Response fields

Response headers

Errors

What a call costs — 2 credits per call

Call it from cURL — GET /v1/ringsizeconverter

Resources

Also published for

Call it from Node.js — GET /v1/ringsizeconverter

Resources

Also published for

Call it from Python — GET /v1/ringsizeconverter

Resources

Also published for

Call it from C# / .NET — GET /v1/ringsizeconverter

Resources

Also published for

Call it from Go — GET /v1/ringsizeconverter

Resources

Also published for

Call it from PHP — GET /v1/ringsizeconverter

Resources

Also published for

Call it from Ruby — GET /v1/ringsizeconverter

Resources

Also published for

Zero-code embed — one snippet, no backend

Changelog — Ring Size Converter API

Reference Data

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