Subnet Calculator — Free CIDR/IP Networking Tool

Free subnet calculator. Enter IP and CIDR to get network, broadcast, host range, subnet mask, wildcard, IP class. 100% client-side. 100% serverless.

🔒 100% Private
Completely Free
🌐 Runs in Browser
📦 Export Ready

Subnet Calculator — Free CIDR/IP Networking Tool

Tool Workspace

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  1. Enter IP — Type an IPv4 address (e.g., 192.168.1.0).
  2. Enter CIDR — Enter the prefix length (0-32).
  3. Calculate — See network, broadcast, host range, masks, class, and binary.

Subnet Calculator — CIDR/IP Networking Tool

The Subnet Calculator is an essential networking tool that takes an IPv4 address and CIDR prefix and computes network address, broadcast address, host range, subnet mask, wildcard mask, total and usable hosts, IP class, private/public status, and binary representation.

What is Subnetting?

Subnetting divides a large network into smaller sub-networks (subnets). Each subnet has its own network address and broadcast address. The CIDR prefix length determines how many bits are used for the network portion versus the host portion of the address.

Key Concepts

  • Network Address — First address in the subnet, identifies the network.
  • Broadcast Address — Last address, used to send to all hosts in the subnet.
  • Subnet Mask — Determines which portion of the IP is network vs host.
  • Wildcard Mask — Inverse of subnet mask, used in ACLs and OSPF.
  • CIDR Prefix — Number of bits in the network portion (e.g., /24 = 256 addresses).

Features

  • Complete Breakdown — Network, broadcast, host range, masks, class, binary.
  • Private Detection — Identifies RFC 1918 private addresses.
  • IP Classification — Shows Class A/B/C/D/E.
  • Copy All — One-click copy of complete results.

Privacy

All calculations run in your browser. No IP data is transmitted.

Frequently Asked Questions

What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation uses a prefix length after the IP address (e.g., /24) to indicate the subnet mask. /24 means the first 24 bits are the network portion a.k.a. 255.255.255.0.

What is the difference between total and usable hosts?

Total hosts = 2^(32-prefix). Usable hosts = total - 2, because the network address and broadcast address cannot be assigned to hosts. Exception: /31 and /32 subnets follow special rules.

What are private IP ranges?

10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 are private (RFC 1918) ranges, used in local networks and not routable on the internet.

Is my data uploaded?

No. All calculations run 100% in your browser.