cidr

Calculate subnet info

$ ipcalc [192.168.1.0/24]

$ sipcalc [10.0.0.0/8]

$ ipcalc [192.168.1.0] [255.255.255.0]

$ ipcalc [192.168.1.0/24] [/27]

ipcalc [options] address[/prefix] [netmask]
sipcalc [options] address[/prefix]

CIDR calculators compute network information from IP addresses and subnet masks. Common tools include ipcalc, sipcalc, and whatmask. They calculate network and broadcast addresses, usable host ranges, wildcard masks, and other subnet parameters.
These utilities are essential for network planning, subnetting, and troubleshooting. Given an IP address and prefix length (or netmask), they break down all relevant addressing details. Some tools also support IPv6, subnet splitting, and supernetting.
Available on most Linux distributions via package managers. For visual CIDR notation exploration, online tools like cidr.xyz provide interactive visualizations.

-n

Don't show hostname

Don't show broadcast

Split network for hosts

Calculate needed prefix

-a

All information

Resolve hostnames

IPv4 only

IPv6 only

Network

First address in subnet

Last address in subnet

Usable address range

Number of usable addresses

Cisco wildcard mask

Use for network planning and troubleshooting. Online tools available at cidr.xyz for visualization.

ip(8), ifconfig(8), netmask(1)