Navigating the complexities of network configuration can be challenging. Our free IPv4 Subnet Calculator simplifies the process by giving you all the crucial network information you need in an instant. Just enter an IP address and CIDR prefix to instantly determine the network address, broadcast address, host range, and more.

How to Use Our IPv4 Subnet Calculator

Getting detailed network information is fast and straightforward with our tool. Just follow these steps:

1. Enter a valid IPv4 address (e.g., 192.168.1.100) into the "IP Address" field.
2. Enter the CIDR prefix length (e.g., 24) into the field after the "/" symbol.
3. The table will automatically update with the complete subnet details as you type. No need to click a button!

Input Example and Result

If you need to analyze the network for the IP address 10.10.50.123 on a network with a /22 prefix, you would enter that into the tool.

Input:

IP Address: 10.10.50.123
CIDR:       /22

Resulting Calculation:

Network Address:   10.10.48.0
Broadcast Address: 10.10.51.255
Host Range:        10.10.48.1 - 10.10.51.254
Subnet Mask:       255.255.252.0
Usable Hosts:      1022

Understanding IPv4 Subnetting

IPv4 subnetting is the process of dividing a single, large IP network into smaller, more manageable sub-networks, or "subnets." An IP address (like 192.168.1.100) is a unique identifier for a device on a network. It has two parts: the network portion and the host portion. The subnet mask is what defines which part is which.

A subnet mask can be written in dot-decimal notation (e.g., 255.255.255.0) or, more commonly today, in CIDR (Classless Inter-Domain Routing) notation (e.g., /24). The CIDR number represents the number of bits used for the network portion of the address. Our calculator uses the IP and CIDR to determine key addresses:

• Network Address: The first address in a subnet. It represents the network itself and cannot be assigned to a device.
• Broadcast Address: The last address in a subnet. It's used to send messages to all devices on that specific subnet simultaneously.
• Host Range: The range of IP addresses between the network and broadcast addresses that can be assigned to individual devices like computers and servers.
• Usable Hosts: The total number of available IPs in the host range.

Subnetting is crucial for modern networking as it improves efficiency, enhances security by isolating networks, and allows for better organization of network resources.

Frequently Asked Questions (FAQ)

Q1: What is CIDR notation?

CIDR (Classless Inter-Domain Routing) notation is a compact way to represent a subnet mask. The number after the slash (e.g., /24) indicates how many bits of the 32-bit IPv4 address are part of the network prefix. A /24 corresponds to a subnet mask of 255.255.255.0, while a /16 corresponds to 255.255.0.0, and so on.

Q2: Why are there two fewer usable hosts than total hosts?

In any given subnet, two addresses are reserved for special purposes and cannot be assigned to individual devices. The first IP address is the Network Address (which identifies the subnet itself), and the last IP address is the Broadcast Address (used to send data to all hosts on the subnet). Therefore, the number of "usable" IPs is always the total number of hosts minus these two.

Q3: Can this calculator be used for IPv6?

No, this tool is designed specifically for IPv4 addresses, which are 32-bit addresses written in dot-decimal format. IPv6 addresses use a completely different 128-bit format (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334) and have different subnetting rules and tools.