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FREE ONLINE TOOL

Free CIDR
Calculator

Open CIDR Calculator and complete the task in your browser, free of charge.

Open this tool in its own window ↗

FreeUse this tool without paying.No sign upStart with the tool right away.Clear stepsRead the tool’s own guidance.

About Free CIDR Calculator

Inspect IPv4 or IPv6 blocks with exact integer math, test membership and overlap, convert ranges to minimal CIDRs, aggregate route lists, split prefixes, and export clean network plans—all locally.

Workspace options

  • Address / prefix
  • CIDR
  • Addresses · one per line
  • Block A
  • Block B
  • Start address

Available actions

  • Inspect
  • Membership & overlap
  • Range ⇄ CIDR
  • Aggregate & split
  • Guide
  • Inspect block