IPv4 Subnet Calculator
Calculate network address, broadcast address, and host range from an IP and subnet mask.
Network address: 192.168.1.0
Broadcast address: 192.168.1.255
Subnet mask: 255.255.255.0 (/24)
Wildcard mask: 0.0.0.255
First usable address: 192.168.1.1
Last usable address: 192.168.1.254
Usable host count: 254
Usage examples
Planning subnets before splitting up a network
When dividing a large network into smaller subnets, work out each subnet's network and broadcast addresses ahead of time.
Checking a router's or server's IP configuration
Given a setting written as 192.168.1.100/24, instantly see how many usable IP addresses that actually covers.
Converting between CIDR and dotted-decimal notation
Enter either a CIDR value like /24 or a dotted mask like 255.255.255.0 and see the same result either way.
Frequently asked questions
Is my IP address sent to a server?
No. All calculation happens entirely in your browser, and what you enter is never sent to a server.
Why do /31 and /32 subnets calculate host counts differently?
A typical subnet excludes the network and broadcast addresses when counting hosts. But /32 is a single address with just one host, and /31 is a special case for point-to-point links (RFC 3021) where both addresses are usable, so these two are calculated separately.
Should I enter the subnet mask as CIDR or dotted notation?
Both work. You can type '24' or '/24', or '255.255.255.0' — it's detected automatically.
What is the wildcard mask used for?
The wildcard mask is the inverse of the subnet mask, and it's commonly used in router access control lists (ACLs) and OSPF configuration to specify an address range.