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 value | new value | ||
|---|---|---|---|
| Start address | 192.168.1.100 | 192.168.0.0 | |
| End address | 192.168.7.255 | 192.168.7.255 | |
| Addresses in range | 1,692 | 2,048 | |
| CIDR | 192.168.0.0/21 | 
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.
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
 
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