Knuckle: Ring Sizer

Size a ring on your screen

Free · In‑App Purchases · Designed for iPad. Not verified for macOS.

Lay a ring you own flat on the screen, match the circle to the band, and read the size. No camera. No jeweler. Knuckle turns your screen into a ring sizer. Lay a ring you already own flat on the display, match the gold circle to the inside of the band, and read the size. That is the whole thing. No camera, no printing, no paper strips to cut out, no trip to a jeweler. Before the first measurement you line a bank or ID card up against an outline, once, so Knuckle learns exactly how large a millimetre is on your particular screen. Every reading after that is true to your device. You get the inner diameter in millimetres next to the sizes people actually ask for - US, UK, EU, Japan, Australia, Hong Kong and Italy. Each result carries an honest confidence band instead of one number pretending to be certain. Sizes are worth keeping. Save one under the person it belongs to, note the finger and the hand, and look it up later while you are standing in the shop. Send a clean size card to whoever is buying. Nothing leaves your device. No account, no sign in, and it all works with the network switched off. Privacy Policy: https://docs.google.com/document/d/e/2PACX-1vTDX9pxPOlUJl_skVUHPi99mAw0y2B2BYd_v1mJkoF3xW3rlOcW5KlYd4t93MMbbGhctSTnBTy7d_l6/pub Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Ratings & Reviews

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The developer, Andrii Bashta, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Linked to You

    The following data may be collected but it is not linked to your identity:

    • Usage Data

Privacy practices may vary, for example, based on the features you use or your age. Learn More

Accessibility

The developer has not yet indicated which accessibility features this app supports. Learn More

Information

Seller
  • Andrii Bashta
Size
  • 12.9 MB
Category
  • Utilities
Compatibility
Requires iOS 26.0 or later.
  • iPhone
    Requires iOS 26.0 or later.
  • iPad
    Requires iPadOS 26.0 or later.
  • Mac
    Requires macOS 26.0 or later and a Mac with Apple M1 chip or later.
  • Apple Vision
    Requires visionOS 26.0 or later.
Languages
  • English
Age Rating
4+
In-App Purchases
Yes
Copyright
  • © 2026 Andrii Bashta
  • Privacy Policy

    • Supports

    • Family Sharing

      Some in-app purchases and subscriptions may be shareable with your family group when Family Sharing is enabled. Learn More

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