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CIDR Range Calculator

Enter any IPv4 CIDR block and get network, broadcast, usable host range, and address counts instantly.

This tool runs 100% in your browser. Your data is never uploaded, stored, or logged.

Range details

Enter a CIDR block to see its network, broadcast, usable range and host count.

About this tool

CIDR notation packs a whole network definition into one slash: 192.168.1.0/24. This calculator expands it into everything you actually need — network and broadcast addresses, first and last usable hosts, total and usable address counts, wildcard mask and binary netmask.

It also classifies the block (private, public, loopback, multicast…) and tells you when the IP you typed is a host inside the block rather than the network address.

How to use it

  1. Type a CIDR block like 10.0.0.0/16.
  2. Results appear instantly as you type.
  3. Note the usable range — network and broadcast addresses are excluded on /30 and larger prefixes.
  4. Use the wildcard mask for ACLs (Cisco-style) if needed.

Useful ways to apply it

  • Planning firewall and security-group rules.
  • Splitting an office network into subnets.
  • Checking whether two IPs share a subnet.
  • Understanding cloud VPC CIDR assignments.

Frequently asked questions

Why are there 254 usable hosts in a /24, not 256?
The first address is the network identifier and the last is the broadcast address; neither can be assigned to a host. /31 and /32 are special cases used for point-to-point links and host routes.
What is a wildcard mask?
The bitwise inverse of the netmask (0.0.0.255 for /24), used by some ACL syntaxes to express which bits may vary.
Does it support IPv6?
Not yet — this calculator is IPv4-only. IPv6 support is on the roadmap.

Privacy

This tool runs 100% in your browser. Your data is never uploaded, stored, or logged.