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CIDR Subnet Calculator
Network address, broadcast, mask, wildcard and usable host range for any IPv4 CIDR block.
About this tool
Subnetting is a daily task for network engineers, cloud architects and anyone configuring firewalls, VPCs or VPNs. This calculator takes an IPv4 address in CIDR notation, such as 192.168.10.77/26, and returns the network address, broadcast address, subnet mask, wildcard (inverse) mask, first and last usable host, total addresses and usable hosts.
It handles the edge cases that many calculators get wrong: a /31 point-to-point link (RFC 3021) has two usable addresses and no broadcast, and a /32 identifies a single host. It also reports the legacy class and whether the address falls into a private, loopback or link-local range.
All arithmetic uses unsigned 32-bit integers in your browser. Nothing you enter is transmitted anywhere.
How to use it
- Enter an IPv4 address followed by a slash and prefix length, for example 10.0.0.5/22.
- Press Calculate.
- Copy the network, mask or host range into your firewall rule or cloud console.
Frequently asked questions
What is the difference between a subnet mask and a wildcard mask?
A wildcard mask is the bitwise inverse of the subnet mask. Cisco ACLs and OSPF statements use wildcard masks.
How many usable hosts does a /24 have?
256 total addresses, 254 usable, because the network and broadcast addresses are reserved.
Does it support IPv6?
Not yet. This tool covers IPv4 only.
Results are provided for general information. Please read our disclaimer.