Subnet Calculator

What Is a Subnet Calculator?

A subnet calculator is an IPv4 network planning tool with four modules: network calculation, mask conversion, reverse mask lookup and subnet division. All calculations run locally in the browser and your input is never uploaded to a server.

Main Features

• Network calculator: compute network address, broadcast address, usable host range and binary/hex forms from an IP and CIDR or mask
• Mask conversion: convert between prefix length, dotted-decimal, binary and hexadecimal
• Reverse mask lookup: recommend the smallest mask that satisfies the required number of hosts
• Subnet division: split a network into a power-of-two number of subnets and list each subnet

Use Cases & Notes

Ideal for network planning, router configuration and teaching demos. The number of subnets must be a power of two (2/4/8/16...).

How to Use

1. Select the corresponding tab
2. Enter the IP, CIDR or mask as prompted
3. Click Calculate to view the results and copy them if needed