CIDR Calculator
Calculate subnet details, network range, broadcast addresses, and usable hosts from an IP and prefix.
Networking
Subnet CIDR Block
192.168.1.0/24
Usable Host IP Range
192.168.1.1
to 192.168.1.254
to 192.168.1.254
Subnet Mask
255.255.255.0
Usable Hosts
254/ 256 total
Subnet Details Table
CIDR Notation
192.168.1.0/24
Netmask (Dotted Decimal)
255.255.255.0
Wildcard Mask
0.0.0.255
Network Address
192.168.1.0
Broadcast Address
192.168.1.255
First Usable Host
192.168.1.1
Last Usable Host
192.168.1.254
Total Address Count
256
Usable Hosts Count
254
Binary Representation (Blue = Network Prefix bits, Gray = Host bits)
IP Address:11000000.10101000.00000001.000000.01
Subnet Mask:11111111.11111111.11111111.000000.00
Network ID:11000000.10101000.00000001.000000.00
What is CIDR?
CIDR (Classless Inter-Domain Routing) is a method for allocating IP addresses and routing Internet Protocol packets. It replaces the older system based on Class A, Class B, and Class C networks.
CIDR notation describes an IP address and its associated routing prefix. It uses the format: IP_ADDRESS/PREFIX_LENGTH.
For example, 192.168.1.100/24 means:
- The IP address is
192.168.1.100. - The subnet routing prefix has a length of
24bits (equivalent to subnet mask255.255.255.0).
What does this CIDR Subnet Calculator do?
Input an IP address (IPv4) and select a prefix length (subnet mask) to immediately calculate:
- Network CIDR block
- Subnet Mask in dotted-decimal format
- Network Address (the first address in the block)
- First Usable Host IP
- Last Usable Host IP
- Broadcast Address (the last address in the block)
- Total Hosts and Usable Hosts count
- Binary representation of the IP, network, and mask, which is highly useful for learning subnetting.