Subnet Calculator

Calculate subnet masks, network addresses, broadcast addresses, and usable host ranges for any IP address and CIDR.

Enter IP Details

Network Address

192.168.1.0

Subnet Mask

255.255.255.0

Broadcast Address

192.168.1.255

CIDR Notation

/24

First Usable Host

192.168.1.1

Last Usable Host

192.168.1.254

Total Addresses

256

Usable Hosts

254

Understanding IP Subnetting

The subnet calculator helps network engineers and IT professionals quickly determine network boundaries, usable host ranges, and subnet masks for any given IP address and prefix length.

Common Subnet Sizes

  • /24 - 254 usable hosts (255.255.255.0)
  • /25 - 126 usable hosts (255.255.255.128)
  • /26 - 62 usable hosts (255.255.255.192)
  • /27 - 30 usable hosts (255.255.255.224)
  • /28 - 14 usable hosts (255.255.255.240)

Subnet Calculator FAQ

What is a subnet mask?▼

A subnet mask divides an IP address into network and host portions. It determines which part identifies the network and which identifies individual devices. Common masks: /24 = 255.255.255.0, /16 = 255.255.0.0.

What is CIDR notation?▼

CIDR (Classless Inter-Domain Routing) notation uses a slash followed by the number of network bits. For example, /24 means 24 bits for the network, leaving 8 bits (256 addresses) for hosts.

How many usable hosts in a /24 subnet?▼

A /24 subnet has 256 total addresses (2^8), but 2 are reserved (network address and broadcast), giving 254 usable host addresses.