Subnetting Made Simple: A Visual Guide to IP Subnets

What is Subnetting?

Subnetting divides a large network into smaller, more manageable sub-networks (subnets). Think of it like dividing a building into floors and rooms - each subnet is a separate "room" on your network.

Calculate subnets instantly with our Subnet Calculator.

IP Addresses in Binary

Every IP address is actually a 32-bit binary number:

192.168.1.0
= 11000000.10101000.00000001.00000000

Each of the four octets ranges from 0-255 (8 bits each).

Subnet Masks Explained

A subnet mask determines which part of an IP address identifies the network and which part identifies the host (individual device).

IP:          192.168.1.100
Subnet Mask: 255.255.255.0
             |||||||||||_____ Host part (last octet)
             ||||||||________ Network part (first 3 octets)

Common subnet masks:

CIDR Notation

CIDR (Classless Inter-Domain Routing) notation uses a slash followed by the number of network bits:

• /24 means 24 bits for network, 8 bits for hosts = 254 usable addresses
• /25 means 25 bits for network, 7 bits for hosts = 126 usable addresses
• /32 means all 32 bits are network = single host address

How to Calculate Subnets

Step 1: Determine hosts needed

How many devices need IP addresses on this subnet?

Step 2: Find the right CIDR

Number of usable hosts = 2^(32-CIDR) - 2 (subtract network and broadcast addresses)

Step 3: Calculate network boundaries

For 192.168.1.0/26:

• Block size: 256 - 192 = 64
• Subnet 1: 192.168.1.0 - 192.168.1.63
• Subnet 2: 192.168.1.64 - 192.168.1.127
• Subnet 3: 192.168.1.128 - 192.168.1.191
• Subnet 4: 192.168.1.192 - 192.168.1.255

Private IP Ranges

These ranges are reserved for internal networks:

• 10.0.0.0/8 - Class A (16M addresses)
• 172.16.0.0/12 - Class B (1M addresses)
• 192.168.0.0/16 - Class C (65K addresses)

Real-World Subnetting Example

Your office has 4 departments: Engineering (45 people), Sales (20), Marketing (12), and Management (8).

Solution:

• Engineering: /26 (62 hosts) - 192.168.1.0/26
• Sales: /27 (30 hosts) - 192.168.1.64/27
• Marketing: /28 (14 hosts) - 192.168.1.96/28
• Management: /28 (14 hosts) - 192.168.1.112/28

Tools for Network Work

• Subnet Calculator - calculate subnets, CIDR, and host ranges
• IP Lookup - find information about any IP address
• Number Base Converter - convert between decimal, binary, and hex
• Binary Calculator - perform bitwise operations