IP Subnet Calculator

Calculate IP subnets, CIDR notation, and network ranges

IP Subnet Calculator

IP Address

CIDR Prefix

Subnet Mask

Calculation Results

Usable Hosts

Total Hosts

IP Class

Type

Network Address -

Broadcast Address -

First Usable Host -

Last Usable Host -

Subnet Mask -

Wildcard Mask -

CIDR Prefix -

Binary IP -

Binary Mask -

Quick Reference

Common Subnets (CIDR / Mask / Hosts)

/24255.255.255.0254

/16255.255.0.065,534

/8255.0.0.016,777,214

/32255.255.255.2551

All calculations are performed locally in your browser. No data is sent to any server.

Usage Examples

Home Network

Calculate a typical home network subnet with 192.168.1.0/24, providing 254 usable host addresses.

Corporate Network

Analyze a large corporate network with 10.0.0.0/8, covering over 16 million host addresses.

Data Center VLAN

Plan a data center VLAN with 172.16.0.0/20, providing 4,094 usable addresses for servers.

Features

Complete Subnet Info

Calculate network address, broadcast, host range, wildcard mask, and CIDR notation instantly

Subnet Subdivision

Break down any network into smaller subnets to plan your IP address allocation

Binary Representation

View binary representations of IP addresses and subnet masks for better understanding

Client-Side Processing

All calculations run in your browser using JavaScript, no server communication needed

How to Use?

Enter IP Address

Enter an IPv4 address and select a CIDR prefix length or type the subnet mask directly.

View Results

See the complete subnet information including network, broadcast, host range, and more.

Subdivide Subnets

Optionally break the network into smaller subnets for detailed IP planning and allocation.

Frequently Asked Questions

CIDR (Classless Inter-Domain Routing) notation expresses an IP address and subnet mask in one compact form: 192.168.1.0/24. The number after the slash is the prefix length — how many bits of the 32-bit address are the network part. /24 means 24 network bits and 8 host bits, giving 256 total addresses (2^8). Common values: /8 = 16.7M hosts, /16 = 65,536 hosts, /24 = 256 hosts, /28 = 16 hosts.

Two addresses in every subnet are reserved: the first address is the network address (identifies the subnet itself) and the last is the broadcast address (packets sent here reach all hosts in the subnet). Neither can be assigned to a device. So a /24 has 256 total addresses but 254 usable (256 - 2). A /30 has 4 total but only 2 usable — the minimum for a point-to-point link.

Three ranges are reserved for private use and not routed on the public internet: 10.0.0.0/8 (Class A, ~16.7 million addresses), 172.16.0.0/12 (Class B range, 172.16.x.x through 172.31.x.x, ~1 million addresses), and 192.168.0.0/16 (Class C range, ~65,536 addresses). Home routers use 192.168.x.x. Corporate networks commonly use 10.x.x.x. Cloud VPCs can use any private range.

A wildcard mask is the bitwise inverse of the subnet mask. Example: subnet mask 255.255.255.0 → wildcard 0.0.0.255. Wildcard masks are used in Cisco ACLs, OSPF area configurations, and firewall rules to define which bits of an address must match. A 0 bit means "must match," a 1 bit means "any value." The wildcard 0.0.0.255 matches any host in the /24 network.

The broadcast address is the last address in a subnet — all host bits set to 1. A packet sent to the broadcast address is delivered to every device in the subnet. It cannot be assigned to any host. For 192.168.1.0/24, the broadcast is 192.168.1.255. For 10.0.0.0/8, the broadcast is 10.255.255.255.

To split a network into N equal subnets, increase the prefix length by log2(N) bits. Example: divide 192.168.1.0/24 into 4 subnets: /24 + 2 bits = /26. Each /26 has 64 total addresses (62 usable): 192.168.1.0/26, 192.168.1.64/26, 192.168.1.128/26, 192.168.1.192/26. The Subdivision tool below the results calculates all sub-ranges automatically.

Legacy IP classes: Class A (first octet 1-126, default /8 mask, e.g., 10.0.0.0/8), Class B (first octet 128-191, default /16, e.g., 172.16.0.0/16), Class C (first octet 192-223, default /24, e.g., 192.168.0.0/24). Classful addressing is largely obsolete — modern networks use CIDR and can use any prefix length. The tool shows the IP class as a reference point.

No. All subnet calculations run in your browser via JavaScript. No IP addresses or network data are transmitted. Works offline.

What Is IP Subnet Calculator?

Type an IPv4 address and a CIDR prefix and instantly see the network address, broadcast, usable host range, wildcard mask, IP class, binary representations, and whether it is private or public.

Subnet Subdivision

Need to carve a /24 into four /26s? The subdivision tool breaks any network into smaller, equal-sized subnets and lists each one with its range and host count -- handy for VLAN planning.

Who Uses This?

Network engineers planning IP allocation, sysadmins setting up VLANs, students studying for the CCNA, and devops folks configuring cloud VPCs. Basically anyone who works with IPv4 subnetting.

Quick Reference

The sidebar shows common CIDR values with their masks and host counts so you can eyeball the right prefix length without memorizing the table.

Privacy

Every calculation runs client-side in JavaScript. No IP addresses or network data are sent to any server.

Security and Privacy

Your data security is our priority

Local Processing

All processing happens in your browser

No Data Transfer

Your data is not sent to our servers

No Data Storage

No data is stored or shared

SSL Encryption

SSL encryption for secure connection

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IP Subnet Calculator