Free Tools / Subnet & CIDR Calculator
Subnet & CIDR Calculator
Enter an IPv4 or IPv6 address with a prefix to get the network and broadcast address, usable host range, netmask, wildcard mask, host count, and binary, then split the network into smaller subnets. It all runs in your browser.
Frequently asked questions
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation writes a network as an address followed by a slash and a prefix length, such as 192.168.1.0/24. The prefix is the number of leading bits that make up the network portion; the rest identify hosts.
How many usable hosts are in a /24?
A /24 has 256 addresses and 254 usable hosts, because the network and broadcast addresses are reserved. A /31 is a special case (RFC 3021) that provides 2 usable addresses for point-to-point links.
What is a wildcard mask?
A wildcard mask is the bitwise inverse of the subnet mask, used in access control lists on some network gear: a 1 bit means "ignore this bit" and a 0 bit means "match exactly".
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