Subnet Calculator
A subnet calculator computes network address, broadcast address, host range, subnet mask, and total hosts for any IPv4 CIDR block.
Enter any IPv4 address in CIDR notation and the calculator instantly derives all subnet parameters using bitwise arithmetic. It runs entirely client-side with no server requests. Results include the network address, broadcast address, usable host range, subnet mask, wildcard mask, and the total number of assignable host addresses.
Frequently Asked Questions
What is a subnet?
A subnet is a logical division of an IP network. Subnetting allows network administrators to divide a large network into smaller, manageable segments. Each subnet has a range of IP addresses that devices on that segment can use.
What does CIDR notation mean?
CIDR (Classless Inter-Domain Routing) notation expresses an IP address and its subnet mask together. The number after the slash indicates how many bits are used for the network portion. For example, 192.168.1.0/24 means 24 bits for the network, leaving 8 bits for 256 host addresses.
What is the difference between network address and broadcast address?
The network address is the first address in a subnet and identifies the subnet itself. The broadcast address is the last address and is used to send data to all devices on the subnet. Neither can be assigned to individual hosts.
How many usable hosts does a /24 subnet have?
A /24 subnet has 256 total addresses (2 to the power of 8). Subtract 2 for the network address and broadcast address, leaving 254 usable host addresses.
Subnet Calculator
CIDR to network details, instantly
Enter any CIDR block and get the network address, broadcast, usable host range, subnet mask, and total host count. All client-side, nothing sent anywhere.
What is CIDR notation?
CIDR stands for Classless Inter-Domain Routing. It's a way to write an IP address and its subnet mask in a single compact string. The number after the slash is the prefix length: how many bits are fixed for the network portion.
So 192.168.1.0/24 means the first 24 bits (192.168.1) are the network, and the last 8 bits are for hosts. That gives you 256 addresses, 254 usable (the network address and broadcast are reserved).
The smaller the prefix number, the bigger the network. /8 covers 16 million addresses. /30 covers just 4.
Common subnet sizes at a glance
Private IP ranges
Three IP ranges are reserved for private networks (RFC 1918). They can't be routed over the public internet.
10.0.0.0/8Class A private — 10.x.x.x172.16.0.0/12Class B private — 172.16.x.x through 172.31.x.x192.168.0.0/16Class C private — 192.168.x.x (your home network)Questions people actually search for
What's the difference between network address and broadcast address?
The network address is the first address in the block. You can't assign it to a device. The broadcast address is the last one and is used to send packets to all hosts on the subnet simultaneously. Both are reserved, which is why a /24 has 254 usable hosts instead of 256.
What is a wildcard mask?
It's the inverse of the subnet mask. Where the subnet mask has 1s, the wildcard has 0s and vice versa. Wildcard masks are used heavily in Cisco ACLs and OSPF configurations. For a /24, the wildcard is 0.0.0.255.
How do I split a /24 into smaller subnets?
Each extra bit you add to the prefix halves the network. A /24 becomes two /25s, four /26s, eight /27s, etc. This is called subnetting. Use this calculator to figure out the specific ranges before you configure anything.