IPv4 Subnet Calculator
Instantly calculate complex network routing data including Subnet Masks, Usable Host Ranges, Broadcast Addresses, and CIDR notations.
How to Use
- Type your standard IPv4 address into the IP Address box (e.g.,
192.168.1.1or10.0.0.5). - Select your network size using the Subnet Mask / CIDR dropdown. This dropdown displays the CIDR notation (like
/24) alongside the standard decimal mask (like255.255.255.0). - Click Calculate to instantly generate the mathematical network boundaries, including your exact usable host range, broadcast address, and wildcard mask.
Features
Exact Ranges
Calculates the absolute first and last usable IP addresses for assigning to hardware.
Wildcard Masks
Generates the inverse wildcard mask required for advanced Cisco routing protocols like OSPF.
Class Detection
Automatically identifies if your network falls into the traditional Class A, B, or C ranges.
Privacy First
Your network IPs are never uploaded to a server. The complex math runs directly on your CPU.
Understanding Subnets and CIDR
An IP address on its own (like 192.168.1.50) is meaningless without a Subnet Mask. The subnet mask is the mathematical boundary that tells the computer exactly how large the network is. It splits the IP address into two parts: the Network ID (which identifies the entire group of computers) and the Host ID (which identifies the specific computer within that group).
CIDR Notation (Classless Inter-Domain Routing): Instead of writing out a massive subnet mask like 255.255.255.0, network engineers use CIDR shorthand. The CIDR number represents exactly how many binary "1" bits are in the subnet mask. Therefore, a /24 network means the first 24 bits are dedicated to the network, leaving 8 bits for the hosts (allowing 256 total hosts).
The Network Engineering Suite
If you are assigning IP addresses to new hardware on your network, use the MAC Address Generator to create dummy physical addresses for testing firewall rules. Need to generate complex passwords for your new routers? Try the Random Password Generator. Need to convert IPv4 blocks to raw binary? Use the Binary Code Translator.
Frequently Asked Questions
Why are there two less 'Usable Hosts' than 'Total Hosts'?
In every IPv4 network, the very first IP address is strictly reserved to identify the Network itself, and the very last IP address is strictly reserved for the Broadcast Address (used to send messages to every computer simultaneously). Therefore, a /24 network has 256 total IPs, but only 254 are usable for actual computers.
What is a Wildcard Mask?
A Wildcard Mask is the exact mathematical inverse of a Subnet Mask. It is heavily used in Access Control Lists (ACLs) and routing protocols like OSPF on Cisco hardware. For example, a subnet mask of 255.255.255.0 has a wildcard mask of 0.0.0.255.
Are my IP addresses saved or tracked?
No. This tool is built entirely in front-end JavaScript. All of the bitwise mathematical calculations are performed securely inside your web browser. No data ever leaves your computer.
Is it free?
Yes, 100% free with no limits.