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Ring Size Converter

Unit Converters

Circumference/diameter to HK, US, EU and JP sizes

Quick Answer

Ring Size Converter: Circumference/diameter to HK, US, EU and JP sizes. HK (China): size = C − 38 · EU/ISO: size = C.

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How to Use

  1. Pick units: switch source and target units in the Ring Size Converter.
  2. Enter a value: results sync both ways instantly — no convert button needed.
  3. Use the reference table: common conversions are listed for instant lookup.
  4. Copy the result: copy the converted value with its unit.

Key Points

  • Ring Size Converter is a free online unit conversion tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: Circumference/diameter to HK, US, EU and JP sizes.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Ring size systems (inner circumference C in mm)

HK (China): size = C − 38 · EU/ISO: size = C
US: size ≈ (C − 36.5) ÷ 2.55 · JP: ≈ (diameter − 11.2) ÷ 0.317 + 1
C = π × diameter

FAQ

How do I use the Ring Size Converter?
Open the page and fill in the input fields — results update automatically. Circumference/diameter to HK, US, EU and JP sizes.
Are the results accurate?
Yes. Standard formulas and conversion factors are used and verified.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. Everything runs locally in your browser.

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Source & Updates

Based on SI conversion factors and international standards. Last updated: 2025-07

Authoritative sources:

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Cite this page: YiJianSuan. Ring Size Converter[EB/OL]. https://www.yijiansuan.com/en/c/convert/ring-size

Results provided by this tool are for reference only and do not constitute professional advice.