CIDR Subnet Reference

Detailed information about IPv4 CIDR notation and subnet masks

CIDR (Classless Inter-Domain Routing) notation is a compact method for specifying IP addresses and their routing suffix. Select a CIDR prefix below to view detailed information about that specific subnet size.

Select a CIDR Prefix

/0 /1 /2 /3 /4 /5 /6 /7 /8 /9 /10 /11 /12 /13 /14 /15 /16 /17 /18 /19 /20 /21 /22 /23 /24 /25 /26 /27 /28 /29 /30 /31 /32

Common CIDR Prefixes

Large Networks

Class A (/8)View details →
Class B (/16)View details →
Class C (/24)View details →

Special Cases

Default Route (/0)View details →
Point-to-Point (/30)View details →
Single Host (/32)View details →

What is CIDR?

CIDR (Classless Inter-Domain Routing) is a method for allocating IP addresses and IP routing. It replaced the previous classful network addressing architecture and helps address the scarcity of IPv4 addresses.

The CIDR notation combines the network address with a suffix that indicates the number of bits in the prefix, for example 192.168.1.0/24.

The suffix "/24" indicates that the first 24 bits are used for the network part, leaving the remaining 8 bits for host addresses within that network.

Interactive Tools

Use our interactive subnet calculator to visualize and manipulate subnets with ease.

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