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IP Subnet Calculator

Calculate the network address, broadcast address, subnet mask, and usable host range from an IPv4 address and CIDR prefix.

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About the IP Subnet Calculator

Break down an IPv4 address and CIDR prefix into its network address, broadcast address, subnet mask, and usable host range.

How the IP Subnet Calculator works

Subnetting splits a larger network into smaller, self-contained segments. The CIDR prefix (the "/24" in 192.168.1.0/24) tells you how many of the address's 32 bits are fixed for the network portion — the remaining bits are available for host addresses. A /24 leaves 8 bits for hosts (256 addresses), while a /30 leaves only 2 bits (4 addresses), which is why smaller prefixes describe bigger networks and larger prefixes describe smaller ones. The first address in a subnet is always reserved as the network address and the last as the broadcast address, so usable hosts is always 2 less than the total address count (except for /31 and /32, which are special cases).

How to use the IP Subnet Calculator

  1. Enter an IPv4 address, e.g. 192.168.1.10.
  2. Enter the CIDR prefix length (0-32), e.g. 24.
  3. Press Calculate to see the network address, broadcast address, subnet mask, wildcard mask, usable host range, and total/usable host counts.

Tips for the IP Subnet Calculator

  • A /24 network gives you 254 usable host addresses — the most common size for a home or small office LAN.

Formula used by the IP Subnet Calculator

Number of hosts = 2^(32 − prefix) Usable hosts = 2^(32 − prefix) − 2 (for prefixes ≤ 30)

Example: IP Subnet Calculator

192.168.1.10 with a /24 prefix

  • IPv4 address: 192.168.1.10
  • CIDR prefix: /24

Result: Network 192.168.1.0, broadcast 192.168.1.255, 254 usable hosts

A /24 prefix fixes the first 24 bits, leaving 8 bits (256 addresses) for hosts; removing the network and broadcast addresses leaves 254 usable addresses from 192.168.1.1–192.168.1.254.

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