SUBNET CALCULATOR
Professional network calculator with CIDR and subnetting tools
Everything runs locally in your browser. Your data never leaves your device - no uploads, no servers, no tracking.
All processing happens directly on your machine using JavaScript. Close the tab and everything is gone. We literally never see your data.
Calculate mode
Available subnets
CIDR Notation quick reference
Common CIDR notations with their subnet masks and usable host counts for IPv4 networks.
How to use Subnet calculator
Professional network calculation in just 3 simple steps
Full Documentation DocsChoose mode
Select IPv4 or IPv6 protocol
Enter details
Input IP address and prefix
Analyze
View complete network analysis
Professional network analysis features
Everything you need for subnet planning and network design
Dual protocol support
Full support for both IPv4 and IPv6 calculations with seamless mode switching and protocol-specific features.
Binary visualization
View IP addresses, subnet masks, and network addresses in binary format with proper formatting for both IPv4 and IPv6.
Subnet generation
Automatically generate multiple subnets with configurable count, complete with network ranges and host calculations.
Network class detection
Auto-detects IP class (A/B/C/D/E) with quick-fill buttons for Class A, B, C private ranges (10.x, 172.16-31.x, 192.168.x).
CIDR Reference
Built-in CIDR notation reference table with Class A, B, and C network ranges for quick lookup and learning.
Export options
Export results in TXT, CSV, or JSON formats, or copy to clipboard for easy integration with documentation and reports.
Frequently Asked Questions
Everything about subnet calculation
Does this calculator support both IPv4 and IPv6?
Yes! Our calculator fully supports both IPv4 and IPv6 protocols. Simply select your preferred mode at the top, and the interface will adapt to show relevant calculations including binary representation, subnet generation, and address analysis for your chosen protocol.
How do I use the subnet generator?
After calculating your network, switch to the "Subnet List" tab, specify how many subnets you need (up to 256), and click "Generate Subnets". The calculator will automatically create properly sized subnets with no address overlaps, showing network addresses, ranges, and host counts for each subnet.
What is the binary view used for?
The binary view shows IP addresses and subnet masks in binary format, helping you understand how subnetting works at the bit level. For IPv4, octets are separated by periods; for IPv6, hextets are separated by colons. This is especially useful for learning and troubleshooting network configurations.
Can I export calculation results?
Yes! Click the download icon to export results in TXT (human-readable), CSV (spreadsheet-compatible), or JSON (machine-readable) formats. You can also use the copy icon to quickly copy results to your clipboard for pasting into documentation or reports.
What is the difference between IPv4 and IPv6 calculations?
IPv4 uses 32-bit addresses with subnet masks and wildcard masks, while IPv6 uses 128-bit addresses with prefix lengths. IPv6 doesn't have broadcast addresses (using "last address" instead) and includes address scope information (Global, Link-Local, etc.). Both protocols support full subnet generation and binary visualization.
How does the calculation history work?
Every calculation is automatically saved to IndexedDB in your browser. Click the "History" button to view your history, and select any previous calculation to instantly restore it. The calculator automatically detects whether it's an IPv4 or IPv6 calculation and switches modes accordingly.