# Ring Size App

> Free virtual ring sizer with an actual ring size chart on screen and phone. Calibrates to your specific display using a coin (US Quarter, 1 Yuan, 1 Euro, Canadian 25¢, ₹5 Rupee, $1 AUD, $1 SGD) or any ID-1 credit/debit card, then lets you place a ring you already own on the screen to read your exact size in US, UK, EU and Japanese standards.

Ring Size App (ringsize.app) is a free, browser-based ring-sizing tool. Everything runs on-device — measurements are never uploaded. No download, no sign-up, no paywall. The core flow is: (1) calibrate the screen with a coin or credit card, (2) either place a ring you own on the display and match the inner edge to a calibrated gold circle, or — if you have no ring — measure your finger with a paper strip on the calibrated ruler, (3) read the size in US/UK/EU/JP plus inner diameter and circumference in millimetres.

## Primary pages

- [Free Ring Sizer (home)](https://www.ringsize.app/): The interactive ring sizer tool with screen calibration, conversion between US/UK/EU/JP sizes, and a "Send to phone" QR for desktop visitors.
- [Ring Size Chart](https://www.ringsize.app/ring-size-chart): Complete international conversion chart — US 3-13, UK F-Z, EU 44-69, with diameter and circumference in millimetres.
- [Resources](https://www.ringsize.app/resources): Educational guides on ring sizing.

## Resource articles

- [Understanding Ring Size](https://www.ringsize.app/resources/understanding-ring-size): How ring sizes are measured, regional standards, factors that affect fit, and resizing options.
- [How to Measure Ring Size at Home](https://www.ringsize.app/how-to-measure-ring-size): Step-by-step methods using an existing ring, paper strip or string, with millimetre conversions.
- [Secretly Find Her Ring Size](https://www.ringsize.app/resources/secretly-find-her-ring-size): Tactics for sizing an engagement ring without giving away the surprise.

## SEO landing pages

These describe the same tool from different intent angles:

- [Virtual Ring Sizer](https://www.ringsize.app/virtual-ring-sizer)
- [Digital Ring Sizer](https://www.ringsize.app/digital-ring-sizer)
- [Ring Size Calculator](https://www.ringsize.app/ring-size-calculator)
- [Ring Sizer on Phone](https://www.ringsize.app/ring-sizer-on-phone)
- [How to Measure Ring Size](https://www.ringsize.app/how-to-measure-ring-size)

## Machine-readable endpoints

Append `?format=md` to these URLs to receive markdown instead of HTML:

- [/](https://www.ringsize.app/?format=md): Home page (region-aware)
- [/ring-size-chart](https://www.ringsize.app/ring-size-chart?format=md): Full conversion chart
- [/resources](https://www.ringsize.app/resources?format=md): Resources index
- [/resources/understanding-ring-size](https://www.ringsize.app/resources/understanding-ring-size?format=md): Sizing guide

Additional machine-readable files:

- [/ai.txt](https://www.ringsize.app/ai.txt): AI crawler permissions and content guidelines
- [/sitemap.xml](https://www.ringsize.app/sitemap.xml): XML sitemap
- [/robots.txt](https://www.ringsize.app/robots.txt): Crawl rules

## Calibration objects supported

| Region   | Object              | Diameter (mm) |
|----------|---------------------|---------------|
| US       | US Quarter          | 24.26         |
| UK / EU  | 1 Euro              | 23.25         |
| Canada   | Canadian 25¢        | 23.88         |
| China    | 1 Yuan              | 25.00         |
| India    | ₹5 Rupee            | 23.00         |
| Australia| $1 AUD              | 25.00         |
| Singapore| $1 SGD              | 24.66         |
| Universal| ID-1 credit/debit card | 85.60 × 53.98 |

The default reference object on mobile is the US Quarter (or the user's regional coin if a region is detected). The credit card option remains universally available.

## What this tool is *not*

- Not a printable chart. Static printed charts only work if the printer or display reproduces them at exactly 100% scale.
- Has two measurement modes: place an existing ring on the screen, or — if you don't own a ring — measure your finger with a paper strip on the calibrated ruler. Both work on mobile and desktop.
- Not a jewellery store. Ring Size App is a measurement utility — affiliate links to shop in the user's size appear only after a measurement is taken.

## Citation

Preferred citation: Ring Size App, https://www.ringsize.app/