Why are 2 addresses subtracted from total hosts?

The first address in any subnet represents the Network Identifier, and the last address is the Broadcast Address, leaving (2^(32-prefix) - 2) for assignable devices.

HomeToolsCIDR Subnet Calculator

DevOps & IT

CIDR IPv4 Subnet Calculator & IP Range Analyzer

Instant, offline-ready subnetting for DevOps engineers, network architects, AWS VPC planners, and CCNA students.

IPv4 Host Address:

Subnet Mask Prefix (/24):

Network Address (Subnet ID)192.168.1.0

Broadcast Address192.168.1.255

Subnet Mask255.255.255.0

CIDR Prefix Notation/24

First Usable Host IP192.168.1.1

Last Usable Host IP192.168.1.254

Total Usable Hosts254 devices

Total Raw IP Block Size256 IPs

IP Address ClassClass C (Small Network)

Binary Subnet Mask11111111.11111111.11111111.00000000

Full /0 to /32 Subnet Calculations

Network & Broadcast Address Derivation

First and Last Usable Host IPs

Binary & Hexadecimal Subnet Mask Display

How to Use CIDR Subnet Calculator - IPv4 & IPv6 Network Mask & Usable IP Range (Step-by-Step Guide)

No software installation required. Complete your task in 3 easy steps directly in your browser.

Enter IP Address

Type an IPv4 address (e.g., 192.168.1.50 or 10.0.0.1).

Select CIDR Prefix

Pick your subnet bitmask from /8 (255.0.0.0) to /32 (single host).

View Subnet Breakdown

Instantly view Network Address, Broadcast, First/Last Usable Host, and Total IPs.

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CIDR Subnet Calculator - IPv4 & IPv6 Network Mask & Usable IP Range Architecture

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Got Questions?

Frequently Asked Questions

Classless Inter-Domain Routing (CIDR) represents an IP address and its associated network mask by appending a slash and the number of leading 1-bits (e.g., /24 equals 255.255.255.0).