Free Network Tools That Work Everywhere

Fast subnet calculators and references for network engineers. Every result is shareable by link, works without JavaScript, and never shows you an ad.

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Calculators & tools

Network, broadcast, host range, wildcard mask and binary breakdown for any IPv4 CIDR block.

Expand or compress any address, inspect prefixes and count /64 subnets instantly.

Convert CIDR to inverse masks for Cisco ACLs — in both directions.

Turn an IP range into the smallest list of CIDR blocks. Batch mode included.

Split a network into right-sized subnets from your host requirements, largest first.

Every prefix from /0 to /32 in one printable table. No email gate.

Quick answers for the masks people actually look up — each page includes host counts, ranges, binary math, examples and FAQs:

Every calculation updates the URL. Paste a permalink into tickets, runbooks or Slack instead of screenshots.

Pages are pre-rendered on Cloudflare's edge and every tool computes without client JavaScript where possible.

/31 point-to-point links per RFC 3021, /32 host routes, CGNAT and documentation ranges handled correctly.