IPv4 Subnet Calculator

Inspect an IPv4 CIDR block and its network, mask, broadcast and host range.

About the IPv4 Subnet Calculator

This reference tool expands an IPv4 address and CIDR prefix into common subnet properties.

How to use it

  1. Enter a dotted-decimal IPv4 address.
  2. Enter a CIDR prefix from 0 through 32.
  3. Calculate the block boundaries and address counts.

How it works

The CIDR prefix creates a 32-bit subnet mask. Bitwise masking finds the network boundary and host bits determine the broadcast boundary.

Example

192.168.1.10/24 belongs to network 192.168.1.0 with mask 255.255.255.0 and broadcast 192.168.1.255.

Notes

The calculator treats /31 as a two-address point-to-point block and /32 as one address, rather than applying the traditional network-and-broadcast exclusion.