IP Subnet Range Calculator
Calculate CIDR notation, total IPs, and subnet mask from a start and end IP address.
CIDR Notation192.168.1.0/24
Network Address192.168.1.0
Broadcast Address192.168.1.255
Subnet Mask255.255.255.0
Prefix Length/24
Total IPs256
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FAQ
- How is a CIDR block calculated from a range?
- The CIDR prefix is determined by finding the highest common bit prefix between the start and end IP addresses. The prefix length is the number of matching leading bits, and the network address is the start IP with host bits zeroed out.
- Why does the CIDR block include more addresses than my range?
- CIDR blocks must be power-of-2 aligned and sized. If your start–end range does not align to a power-of-2 boundary, the enclosing CIDR block will be larger than the exact range. Multiple CIDRs may be needed to cover an exact arbitrary range.
- What is the maximum range I can calculate?
- The tool supports all valid IPv4 ranges from 0.0.0.0 to 255.255.255.255, covering up to a /0 CIDR block (all 4,294,967,296 addresses).
Enter a start IP and end IP address to calculate the enclosing CIDR block, total number of IP addresses in the range, and the corresponding subnet mask. Useful for summarizing arbitrary IP ranges into routing entries or firewall rules.