Convert CIDR notation to network addresses, calculate IP ranges, and determine subnet masks.

Quick Answer

CIDR (Classless Inter-Domain Routing) notation, like 192.168.1.0/24, compactly describes an IP network and its size. This tool converts that notation into the network address, broadcast address, subnet mask, usable host range, and total host count.

What is CIDR notation?

The number after the slash is the prefix length — how many bits of the address are fixed as the "network" portion. A /24 fixes the first 24 bits, leaving 8 bits (256 addresses, 254 usable hosts) for individual devices. Smaller prefix numbers mean larger networks: a /16 has far more addresses than a /28.

How to use this tool

Enter an address in CIDR notation, e.g. 10.0.0.0/16 or 192.168.1.0/24.
Click Calculate to see the network address, broadcast address, subnet mask, first/last usable host, and total host count.

Example

192.168.1.0/24 → Network: 192.168.1.0, Broadcast: 192.168.1.255, Mask: 255.255.255.0, Hosts: 254 (192.168.1.1 – 192.168.1.254).

Privacy

All calculations run locally in your browser using plain JavaScript bitwise math. Nothing is sent anywhere.

FAQ

Why is the host count 2 less than the address count?

Every subnet reserves its first address as the network address and its last as the broadcast address — neither is assignable to a host.

What's the difference between a subnet mask and CIDR notation?

They express the same thing two ways: /24 is equivalent to a subnet mask of 255.255.255.0.

🌐 CIDR Calculator