IPv4 range expander

Given a start and an end IPv4 address, this tool calculates a valid IPv4 subnet along with its CIDR notation.

Results

old valuenew value
Start address192.168.1.100192.168.0.0
End address192.168.7.255192.168.7.255
Addresses in range1,6922,048
CIDR192.168.0.0/21

About IPv4 Subnet Calculation

This tool takes a start and end IPv4 address and calculates the smallest subnet that encompasses both addresses. The result is shown in CIDR notation, which is a compact representation of an IP address and its associated network mask.

How CIDR Notation Works

CIDR (Classless Inter-Domain Routing) notation is a compact method for specifying IP addresses and their network masks. It consists of the base IP address of the network, followed by a slash ("/") and a decimal number.

The decimal number is the count of leading 1 bits in the subnet mask. For example:

  • /24 represents a subnet mask of 255.255.255.0
  • /21 represents a subnet mask of 255.255.248.0
  • /16 represents a subnet mask of 255.255.0.0