IP Subnet
Calculate subnets
Network
192.168.1.0
Broadcast
192.168.1.255
Subnet Mask
255.255.255.0
First Usable
192.168.1.1
Last Usable
192.168.1.254
Total Hosts
256
Usable Hosts
254
CIDR Reference:
/8→16M
/16→65K
/24→254
/32→1
Frequently Asked Questions
What is a subnet mask?
A subnet mask divides an IP address into network and host portions. It determines which part of the IP address identifies the network and which part identifies individual devices. Common masks: 255.255.255.0 (/24) for 254 hosts.
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation uses a slash followed by a number (e.g., /24) to indicate how many bits are used for the network portion. /24 means 24 bits for network, 8 bits for hosts (256 addresses).
How to calculate usable IP addresses?
Usable IPs = Total IPs - 2. Subtract network address (first IP) and broadcast address (last IP). For /24 (256 IPs): 256 - 2 = 254 usable addresses. For /30: 4 - 2 = 2 usable (point-to-point links).