How can we help?

How Do Subnets and Subnet Masks Work?


About subnets and subnet masks

A subnet is a block of IP addresses in your network. In IPv4, an end point such as a mobile phone, desktop, or laptop is typically connected to only one subnet and has only one IP address.

Network devices like routers and firewalls, however, can have multiple IP addresses, each in a different subnet. A device knows another device is on the same subnet by looking at the IP and network address (also called your “subnet mask”): If all the IP address bits in the subnet mask match, it’s on the same network. If a device needs anything not on the subnet, it will forward the data to a router, which serves as the external boundary to your subnet.

Subnets were originally determined by a number of different variables, such as how many IP addresses the subnet needs (it’s “network class”). Today, rather than seeing a subnet mask written out in its full form, you’ll typically see CIDR notation.

Using the subnet calculator

Calculating subnet ranges can be a tricky and time consuming process. Most network professionals keep a subnet mask calculator bookmarked because of this.

Auvik’s IP subnet calculator is designed to quickly calculate all the information you might need for both classful and classless addressing.

You can provide the subnet calculator with an IP address and subnet mask, and it will return a number of details about that network.

Outputs to the subnet range calculator include number of usable addresses and their IP ranges, network and subnet mask addresses. You can also see the outputs in two common different notations: netmask dot-decimal and binary.

We hope you get a lot of use out of our online subnet calculator!

Subnet Calculator

Was this article helpful?
0 out of 0 found this helpful
Have more questions? Submit a request