Subnet Calculator - IP and CIDR

This online subnet calculator is the perfect tool for anyone to size and scale their IPv4 networks.

IP address or CIDR block:

Network Masks
Subnet Mask help
Wildcard Mask help
Host Address Range
First Assignable Host help
Last Assignable Host help
Reserved Addresses
Network Address help
Broadcast Address help
Subnet Properties
# Subnet Bits help
# Assignable Hosts help
Download the free subnet chart PDF to use as a printable reference.

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About the Online Subnet Calculator


Network administrators have been using subnetting for decades to make their networks manageable. Subnets allow you to break large networks into smaller subnets, which are logically separated. If something goes wrong in one part of the network, it does not affect other segments.

The design of IP addressing means every time you add a bit to your subnet mask, you divide the subnet in two parts and assign separate networks. This allows you to build and maintain scalable and efficient networks.

Network Calculator and Free API

This online subnet calculator is the perfect tool to help you figure out out what a network address will be or calculate subnets with masks. This online calculator helps you determine whether a network has enough hosts. also provides an easy way of translating between CIDR notation and dotted-decimal format if needed.

Enter your subnet to get the subnet mask, wildcard mask, network/broadcast address, and number of assignable hosts. You can edit the results and save them on an IP address table and print them for reference.

Use the free subnet API to calculate subnets from a terminal or integrate with software. Save a subnet to your NetworkCalc account to manage IP address assignments.

We designed these tools for systems administrators, network engineers, IT specialists, and students. We hope you find them valuable!