Ring Size API — Free Ring Sizer Integration for Jewellers & E-Commerce

Add accurate ring sizing to your online jewellery store, app, or website in minutes — and watch returns drop while conversions climb. The RingSize API is completely free: no signup, no authentication key, no usage limits.

Wrong ring size is the #1 reason customers return jewellery bought online. When shoppers are unsure of their size, they either abandon the cart or guess — and guesses mean returns, refunds, and lost trust. The RingSize API solves this at the source.

  • Fewer returns, lower costs. Let buyers measure their finger directly on their device before placing an order. Accurate sizing reduces size-related returns by up to 40%.
  • Higher conversion rate. Shoppers who know their size buy with confidence. Removing the "I'll measure later" hesitation keeps customers in the checkout flow.
  • All international standards in one call. A single API response includes US, UK, French, Russian/German, Chinese/Israeli, and Italian/Spanish sizes — no manual conversion tables needed.
  • Works on any platform. Pure REST + JSON integrates with WooCommerce, Shopify, Magento, custom React/Vue storefronts, iOS, Android, and React Native apps.
  • Always free. No API keys, no rate limits, no billing surprises. Start using it in production today.
REST https://ringsize.ru/wp-json/aringsizer/v1

Quick Start

Example: Get size by diameter

// Find the closest size to 17.3 mm diameter
fetch('https://ringsize.ru/wp-json/aringsizer/v1/sizes?diameter_mm=17.3')
  .then(r => r.json())
  .then(data => console.log(data));

Example: Calibrate screen

// Calibrate: user dragged the card to 392 CSS px wide
fetch('https://ringsize.ru/wp-json/aringsizer/v1/calibrate', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ card_width_px: 392, device_pixel_ratio: window.devicePixelRatio })
}).then(r => r.json()).then(data => console.log(data));

Endpoints

MethodEndpointDescription
GEThttps://ringsize.ru/wp-json/aringsizer/v1/sizesFind ring size by diameter or circumference
GEThttps://ringsize.ru/wp-json/aringsizer/v1/sizes/allReturn the full international size table
POSThttps://ringsize.ru/wp-json/aringsizer/v1/calibrateCompute mm/px ratio from on-screen card width

Camera API v2

REST: https://ringsize.ru/wp-json/aringsizer/v2

OpenAPI schema: https://ringsize.ru/wp-json/aringsizer/v2/openapi

POST /camera/calibrate

// Camera flow calibration
fetch('https://ringsize.ru/wp-json/aringsizer/v2/camera/calibrate', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ reference_type: 'card', reference_width_px: 392, device_pixel_ratio: 2 })
}).then(r => r.json()).then(data => console.log(data));

POST /camera/measure

// Camera measurement from prepared numeric data
fetch('https://ringsize.ru/wp-json/aringsizer/v2/camera/measure', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    mode: 'ring',
    measurement: { inner_diameter_px: 158.4 },
    calibration: { mm_per_px: 0.109184 },
    confidence: 0.94
  })
}).then(r => r.json()).then(data => console.log(data));

Stability & Versioning

OpenAPI schema: https://ringsize.ru/wp-json/aringsizer/v1/openapi

  • Base path is versioned: /wp-json/aringsizer/v1.
  • Backward-compatible fixes may be shipped inside v1 without changing endpoint names.
  • Breaking changes will be released only under a new major path such as v2.
  • Machine-readable schema is available at https://ringsize.ru/wp-json/aringsizer/v1/openapi.

Error Format

Error example

{
  "code": "missing_param",
  "message": "Provide diameter_mm or circumference_mm",
  "data": {
    "status": 400
  }
}

Usage Policy

  • No API key is required.
  • No hard rate limit is enforced at the moment, but abusive traffic may be blocked at the edge.
  • Please cache /sizes/all on your side if you use it in production.
  • Send only one of diameter_mm or circumference_mm per lookup request.

Changelog

  • v1.1.0 — canonical base URL, dedicated OpenAPI endpoint, normalized numeric output.
  • v1.0.0 — initial public release of size lookup and calibration endpoints.

Interactive Reference

Run live requests right on this page. Edit query params or JSON body and inspect the response below each endpoint.

GET
Lookup size
https://ringsize.ru/wp-json/aringsizer/v1/sizes
Response: —
Ready.
GET
Full size table
https://ringsize.ru/wp-json/aringsizer/v1/sizes/all
Response: —
Ready.
POST
Screen calibration
https://ringsize.ru/wp-json/aringsizer/v1/calibrate
Response: —
Ready.
POST
Camera calibration
https://ringsize.ru/wp-json/aringsizer/v2/camera/calibrate
Response: —
Ready.
POST
Camera measure
https://ringsize.ru/wp-json/aringsizer/v2/camera/measure
Response: —
Ready.
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