Subnet Calculator

Enter an IP address and subnet mask or CIDR prefix to instantly calculate the network address, broadcast address, usable host range, wildcard mask, and total host count.

How to Use the Subnet Calculator

  1. Choose IPv4 or IPv6 using the toggle at the top of the form.
  2. Enter your address using the CIDR Notation field (e.g., 192.168.1.0/24 or 2001:db8::/32), or fill in the separate IP Address and Subnet Mask / Prefix fields.
  3. Press Enter or click Calculate to see results instantly.
  4. For IPv4, results include: Network Address, Broadcast Address, Subnet Mask, Wildcard Mask, Usable Host Range, Total & Usable Host counts, IP Class, Private/Public scope, CIDR notation, and a binary breakdown.
  5. For IPv6, results include: Compressed & Expanded network address, First & Last addresses, total address count, address type, and a reverse-DNS PTR snippet.
  6. Use the Subnet Split section (IPv4 only) to divide a network into equal subnets — enter a new prefix length larger than the parent (e.g., /26 from /24) to see the full split table.
  7. Click any result card to copy its value to the clipboard.
  8. Click 💾 Save to History to save the current calculation. Saved entries appear in the Saved Calculations panel on the right — click any entry to reload it.
  9. Use 💾 Save JSON in the top action bar to export your history to a backup file. Use 📂 Load JSON to restore it on any device.

About This Tool

This subnet calculator works as a CIDR calculator, IP network calculator, and subnetting tool for network engineers, sysadmins, and students. Enter any IPv4 address with a prefix length or subnet mask to instantly calculate the network address, broadcast address, first and last usable host IPs, total hosts, and wildcard mask.

Useful for network segmentation, VLSM (Variable Length Subnet Masking) planning, firewall rule creation, and IP address management (IPAM). All calculations happen instantly in your browser with no software installation required.