Annulus (Circular Ring / Washer) Area Calculator

Calculate the surface area of a circular ring (annulus) A = π × (R² - r²) between outer and inner radii.

How It Works & Processing Standards

Enter values above to calculate results automatically. Check each input field for guidance and units.

Your input data is never sent to any server and is securely processed on your device.

Current Limits

  • Maximum input length: 100,000 characters

Annulus (Circular Ring / Washer) Area Calculator is a 100% free, browser-based online utility. All calculations and file conversions run locally inside your browser (Local-First) without sending data to remote servers, keeping your documents and inputs strictly private.

How to Use Annulus (Circular Ring / Washer) Area Calculator

  1. 1
    Enter Outer Radius (R)Type outer radius.
  2. 2
    Enter Inner Radius (r)Type inner radius (r ≤ R).
  3. 3
    View Ring AreaRead computed ring surface area.

Common Use Cases

  • Calculating contact surface area of automotive brake rotor discs
  • Sizing flat sealing gaskets and metal washers
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