Docs/APIs/Ring Size Converter

Ring Size Converter

Convert ring sizes between international standards

OperationalCredits 1 per callp50 254msReference DataStar

Overview

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.

Endpoint

One host, one path per API. The block below shows this call in four languages; every one of them is the same HTTP request. Making requests covers the timeouts, retries and parameter rules that apply to all of them. The SDKs wrap the same call in a typed client.

GEThttps://api.apiverve.com/v1/ringsizeconverter
curl "https://api.apiverve.com/v1/ringsizeconverter?size=7&from=us" \
  -H "x-api-key: your_api_key_here"
const res = await fetch('https://api.apiverve.com/v1/ringsizeconverter?size=7&from=us', {
  headers: { 'x-api-key': 'your_api_key_here' },
});

if (!res.ok) throw new Error(`${res.status} ${await res.text()}`);

const { data } = await res.json();
console.log(data);
import requests

res = requests.get(
    "https://api.apiverve.com/v1/ringsizeconverter?size=7&from=us",
    headers={"x-api-key": "your_api_key_here"},
    timeout=15,
)
res.raise_for_status()

print(res.json()["data"])
package main

import (
	"fmt"
	"io"
	"net/http"
)

func main() {
	req, _ := http.NewRequest("GET", "https://api.apiverve.com/v1/ringsizeconverter?size=7&from=us", nil)
	req.Header.Set("x-api-key", "your_api_key_here")

	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()

	out, _ := io.ReadAll(res.Body)
	fmt.Println(string(out))
}

Replace your_api_key_here with the key from your dashboard. When the inputs arrive as a list rather than one at a time, batch requests run up to 200 of them through this same API in a single call.

Authentication

Send your key in the x-api-key header. That is the only auth step — there is no token exchange and no per-endpoint scope to configure. Authentication covers creating, rotating and revoking keys.

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.

Parameters

Sent in the query string. Premium parameters are accepted on every plan but only take effect on plans that include them.

ParameterTypeDescription
sizeRequiredstringThe ring size to convert
fromRequiredstringSource region
usukeujpchau

Response

Every API returns the same three top-level keys, so one response handler covers your whole integration: status, error and data. Only data changes shape. Response format covers the envelope, the other output formats and how premium fields are withheld.

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.

FieldTypeExampleDescription
input_diameter_mmnumber17.3Ring diameter in millimeters
circumference_mmnumber54.3Inside circumference of the ring in millimetres
conversionsobject{...}The equivalent size in every supported sizing system
diameter_mmnumber17.3Inside diameter in millimetres
circumference_mmnumber54.3Inside circumference in millimetres
usnumber7US ring size
ukstring"N"UK ring size
euPremiumnumber52EU ring size
jpPremiumnumber17Japanese ring size
chPremiumnumber-22Swiss ring size
auPremiumstring"N"Australian ring size
notestring"Sizes are approximate. For accurate sizing, visit a jeweler."Caveat that sizes are approximate and a jeweller should confirm

Errors

Read the HTTP status first, then error for the specific reason. The body names the parameter that has to change. Error handling covers the full status list and which of them are worth retrying.

StatusMeaningWhat to do
400Input was rejectedRead error; it names the parameter.
401Key missing or invalidCheck the header name and the key value.
403Key valid, but not permittedA key restriction or IP allow-list; see key scoping.
429Rate limited, or out of creditsRead error to tell them apart; see rate limits.

Use cases

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

Other ways to use Ring Size Converter

Set up Ring Size Converter on APIVerve, or reach the same source a different way. Your APIVerve account and credits work on all of them — one key, one balance.

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

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