IPv4 Subnet Calculator: Network, Broadcast and Host Range
Enter any IPv4 address with a CIDR like /24 to get the network address, broadcast address, subnet mask, usable host range and number of hosts.
Open the free Subnet / CIDR Calculator →What is the Subnet / CIDR Calculator?
Network, broadcast, mask, host range and host count for any IPv4 CIDR. It's completely free, needs no sign-up and works on any phone or computer.
Why it's helpful
- All key subnet values at once
- Great for exam practice and real networks
- No more manual binary maths
Who it's for
Network engineers, IT students and system admins.
How to use it
- Type an IP with a prefix, e.g. 10.0.0.5/16.
💻 Open source: this tool is free and open source (MIT License). View the code on GitHub, download it and run it offline.
The bigger picture: Developer
Developers lose a surprising amount of time to small tasks: formatting data, decoding tokens, converting between formats and checking syntax. Fast in-browser tools keep you in flow and keep sensitive data off third-party servers.
What's changing: AI coding assistants now write a lot of code, but developers still need quick, trustworthy tools to inspect and verify what comes out: formatters, validators and decoders matter more, not less.
Frequently asked questions
Why are 2 addresses unusable?
The network and broadcast addresses are reserved, except on /31 and /32.
