PacketHaven Subnet Calculator
A free, browser-based IPv4 subnet calculator for network engineers, IT administrators, and students. No signup, no ads, no data sent to any server — everything runs in your browser.
Features
- Enter networks in CIDR notation (e.g., 192.168.1.0/24) or IP + dotted-decimal mask (e.g., 10.0.0.0 255.255.0.0)
- Split any network from /8 to /30 into equal-size subnets
- View full subnet details: network address, broadcast address, first and last usable host, subnet mask, wildcard mask, CIDR prefix
- Copy results to clipboard or download as CSV
- Retro terminal interface with green-on-black and amber-on-black themes
- Input validation with clear error messages
- Automatic network address normalization for misaligned inputs
- Works offline — no internet connection required after loading
How to Use
- Type a network address in CIDR format (like 192.168.10.0/24) or with a subnet mask (like 10.2.0.0 255.255.0.0) and press Enter.
- Enter the number of subnets you need.
- View the results: a summary of the original network, subnetting parameters, and a detailed table of every subnet.
- Copy or download results for documentation.
Supported Commands
help, example, clear, copy, theme, banner, about
About PacketHaven
PacketHaven provides free networking tools and resources for IT professionals. Visit packethaven.net for more.