What does CIDR / IP Subnet Calculator actually do?

The CIDR calculator takes an IPv4 address and a prefix length and lists the network address, broadcast, netmask, and usable range. It does not scan the network, and IPv6 is only supported if the form has an IPv6 mode. A /32 is a single host.

When should I use CIDR / IP Subnet Calculator?

Use it to check a subnet before you write a security-group rule.

When should I not use CIDR / IP Subnet Calculator?

Do not use it to discover live hosts.

What does CIDR / IP Subnet Calculator not do?

No packets are sent. Usable host count excludes network and broadcast on IPv4 prefixes that have them.

CIDR / IP Subnet Calculator

Calculate network, broadcast, netmask, usable hosts, and binary masks from an IPv4 CIDR. Free online — runs locally, no upload.

IP / CIDR

Prefix length/24

CIDR

192.168.1.0/24

Network

192.168.1.0

Broadcast

192.168.1.255

Netmask

255.255.255.0

Wildcard

0.0.0.255

First host

192.168.1.1

Last host

192.168.1.254

Hosts

254 usable / 256 total

Class

C

Scope

Private / loopback

IP (binary)

11000000.10101000.00000001.00000000

Mask (binary)

11111111.11111111.11111111.00000000

Search tools

CIDR / IP Subnet Calculator