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CIDR Calculator
Explore IPv4 subnet ranges, masks, network addresses, and usable hosts.
Examples: 10.0.0.0/8 · 172.16.4.0/22 · 192.168.1.10/24
Network address
Broadcast address
Subnet mask
First usable host
Last usable host
Total addresses
Wildcard mask
CIDR prefix
Input address type
Subnet bits
Network bitsHost bits
Address space
What is CIDR?
CIDR (Classless Inter-Domain Routing) represents an IPv4 network with a prefix such as
/24. The prefix indicates how many of the 32 address bits identify the network; the remaining bits identify addresses within that subnet. For conventional IPv4 subnets from /0 through /30, usable host count is normally total addresses minus network and broadcast addresses. /31 is commonly used for point-to-point links, and /32 represents one address.