CIDR Calculator

Calculate IPv4 network details from CIDR notation, including subnet mask, network address, broadcast address, host range, and usable hosts.

CIDR Input

Enter an IPv4 address followed by a prefix length, for example 192.168.1.0/24.
Network Address
-
-

CIDR Details

IP Address
-
Prefix Length
-
Subnet Mask
-
Wildcard Mask
-
Broadcast Address
-
IP Class
-

Host Information

Total Addresses
-
Usable Hosts
-
Host Bits
-
First Host
-
Last Host
-

Binary Representation

IP Address
-
Subnet Mask
-

How CIDR Calculation Works

CIDR stands for Classless Inter-Domain Routing. CIDR notation represents an IPv4 network using an IP address and a prefix length, such as 192.168.1.0/24.

Host Bits=32 − Prefix Length
Total Addresses=2Host Bits

For traditional IPv4 networks, two addresses are commonly reserved: the network address and broadcast address. Therefore, the typical number of usable hosts is:

Usable Hosts=Total Addresses − 2

Example: 192.168.1.0/24

A /24network has 24 network bits and 8 host bits.

  • Network address: 192.168.1.0
  • Subnet mask: 255.255.255.0
  • Broadcast address: 192.168.1.255
  • Total addresses: 256
  • Usable hosts: 254
  • First host: 192.168.1.1
  • Last host: 192.168.1.254

CIDR Notes

  • CIDR prefix lengths range from /0 to /32 for IPv4.
  • A larger prefix length creates a smaller address block.
  • A smaller prefix length creates a larger address block.
  • /32 represents a single IPv4 address.
  • /31 is commonly used for point-to-point links.
  • /30 provides four total addresses.
  • /24 provides 256 total IPv4 addresses.