Tools › Networking › IPv4 Subnet (CIDR) Calculator
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IPv4 Subnet / CIDR Calculator
Enter an address in CIDR notation to see the network address, broadcast, subnet mask and usable host range.
How it works
The prefix length after the slash is the number of leading bits that identify the network. A /24 leaves 8 host bits, giving 256 addresses (254 usable, since the first is the network address and the last is the broadcast). A /31 is a special point-to-point link with 2 usable addresses, and /32 is a single host.
Frequently asked questions
How many hosts are in a /24?
256 addresses, 254 of them usable for hosts.
What is a wildcard mask?
The inverse of the subnet mask, used in some ACL and routing configurations.
What are the private IPv4 ranges?
10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16.
Subnet reference
See the subnet cheat sheet for masks and host counts from /8 to /30.