IPv4 Subnet Calculator

How to use this IPv4 subnet calculator

  1. Type a network in CIDR notation (e.g. 192.168.1.0/24).
  2. See the network address, broadcast, subnet mask, and usable host range instantly.
  3. Use this to plan IP allocation or troubleshoot routing.

What does the /24 mean?

The number after the slash is the prefix length — how many bits of the 32-bit IPv4 address are fixed as the network portion. A /24 fixes the first 24 bits, leaving 8 bits (256 addresses) for hosts, of which 254 are usable.

Why are only 254 addresses usable in a /24, not 256?

The first address in the range is reserved as the network address, and the last is reserved as the broadcast address — neither can be assigned to a device.

What's a /31 or /32 used for?

A /31 is commonly used for point-to-point links (2 addresses, no network/broadcast reserved per RFC 3021), and a /32 represents a single host address.