IP Range Calculator

IP Range Calculator - CIDR to IP Address List

Enter a CIDR notation and get the complete list of all IP addresses in the range with first/last IP and total count.

Enter a network address in CIDR notation (e.g., 10.0.1.0/24 or 192.168.0.0/22) into the input field and click calculate. The tool computes and displays the first IP address in the range, the last IP address, and the total count of addresses in that subnet. For smaller subnets (/24 and smaller, 256 addresses or fewer), the tool also generates and displays the complete list of all IP addresses in the range. Larger subnets show only the summary information to avoid overwhelming your browser. All calculations use efficient JavaScript bitwise operations.

Network administrators audit IP address allocation to identify available addresses in existing subnets. Cloud engineers determine how many EC2 instances or VMs can fit in a planned VPC subnet. Security teams generate lists of IP addresses for bulk firewall rule configuration. DevOps engineers populate IP address pools for load balancers or container orchestration. Network planners verify subnet size meets requirements before proposing CIDR blocks to IPAM systems. Penetration testers enumerate all possible host addresses in target network ranges during reconnaissance.

For production use, avoid manually enumerating large subnets—a /16 contains 65,536 addresses which can freeze your browser. Subnets larger than /24 rarely need full enumeration; focus on the first/last IP and total count. Remember that network (first) and broadcast (last) addresses are not usable for hosts in typical configurations. When planning subnet sizes, account for growth but avoid excessive waste—a /20 provides 4,096 addresses but only 4,094 are usable. For datacenter subnets, reserve the first few host addresses for routers, gateways, and infrastructure services.

All processing happens directly in your browser. Your files never leave your device — no server uploads, no cloud storage, no data retention. The tool works offline once loaded, requires no registration, and is completely free with no usage limits.