Subnet Calculator

IP Address CIDR

What is CIDR?

CIDR (Classless Inter-Domain Routing) is a method used to allocate IP addresses and create network masks. CIDR notation such as /24 or /27 defines how many bits are used for the network portion of an IP address.

Subnet Calculator Features

Calculate Network Address
Calculate Broadcast Address
Determine Usable Hosts
Display Subnet Mask
IPv4 CIDR Calculations

Example Calculation

IP Address: 192.168.0.1/24

Subnet Mask: 255.255.255.0
Network: 192.168.0.0
Broadcast: 192.168.0.255
Usable Hosts: 254

Common CIDR Blocks

CIDR	Hosts
/24	254
/25	126
/26	62
/27	30
/28	14
/29	6
/30	2

Frequently Asked Questions

What is a subnet mask?

A subnet mask determines which portion of an IP address represents the network and which portion represents hosts.

Why use CIDR?

CIDR improves IP address allocation efficiency and reduces routing table size.