CIDR and IP Subnet Calculator

Enter an IPv4 CIDR block to calculate network address, broadcast address, usable range, netmask, wildcard mask, and host count.

Reference

CIDR notes

What is CIDR?

CIDR notation combines an IP address with a prefix length, such as 192.168.1.0/24, to describe an IP network range.

How does the CIDR tool work?

The calculator converts an IPv4 address into a 32-bit integer, applies the prefix mask, and derives the network address, broadcast address, netmask, wildcard mask, usable range, and host count.

When should you use CIDR?

  • Planning private network ranges
  • Checking firewall and routing rules
  • Calculating usable host ranges for subnets
  • Documenting infrastructure network blocks

What are the limitations of CIDR?

  • Only IPv4 CIDR blocks are supported
  • Special network rules may vary by provider or environment
  • IPv6 subnet calculations are not included

CIDR examples

private 192.168.10.42/24 -> 192.168.10.0/24
small 10.0.0.4/30 -> 4 total addresses
host 172.16.1.5/32 -> Single-host block
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