IP Subnet Calculator

Network, broadcast, host range and mask for any IPv4 CIDR. Free, no sign-up, works in your browser.

🔒 100% private — processing happens in your browser. Nothing is uploaded.

How to use the IP subnet calculator

  1. Type an IPv4 address with a prefix, e.g. 10.1.2.3/20, or an address and a mask like 10.1.2.3 255.255.240.0.
  2. Or pick the mask from the list.
  3. Read the network address, broadcast, usable host range, host count, wildcard mask and binary form.

Network admins, students studying for CCNA or Network+, and anyone configuring a router, VPN or firewall rule need these numbers. /31 and /32 networks are handled as point-to-point and single-host networks (no broadcast). Private, loopback, link-local and CGNAT ranges are identified automatically.

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