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The Internet Compass

Developer Utilities

CIDR / IP Subnet Calculator

Standard subnet arithmetic — network address, broadcast address, mask and usable host range — from an IP and prefix length.

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Network address
192.168.1.0
Broadcast address
192.168.1.255
Subnet mask
255.255.255.0
First usable host
192.168.1.1
Last usable host
192.168.1.254
Usable hosts
254

How it works

  1. 1Enter an IPv4 address
  2. 2Enter a CIDR prefix length
  3. 3See the full subnet breakdown

Who this is for

  • Planning IP address allocation for a VPC
  • Verifying a subnet's usable host count before provisioning
  • Understanding an existing network's addressing scheme