Netzwerk
IPv4 Range Expander
The IP range calculator enumerates all IP addresses within a given CIDR block or between a start and end IP address. It displays the first address, last address, total count, network address, broadcast address, and usable host range. It is useful for firewall rule planning, network segmentation design, and validating that a given IP falls within an expected range.
What is the IP Range Calculator?
The IP range calculator converts a CIDR notation block (e.g., 10.0.0.0/24) or an arbitrary start-to-end IP pair into the complete list of addresses it contains. For CIDR blocks it additionally identifies the network address (first address in the block, used for routing), the broadcast address (last address, used to reach all hosts in the subnet), and the number of usable host addresses (total minus 2 for network and broadcast). For large ranges only the first and last address and the total count are shown to avoid rendering millions of entries.
How does it work?
Enter a CIDR block (e.g., 192.168.10.0/28) or a start IP and end IP. The tool converts both boundaries to 32-bit integers, computes the range, and lists addresses up to a configurable maximum. For CIDR blocks it also calculates the subnet mask and wildcard mask. The output includes the count of total and usable addresses. You can toggle between a full list view and a summary view for large ranges.
Typical Use Cases
- Listing all IP addresses in a /28 subnet for firewall allowlist configuration
- Verifying whether a specific IP falls within an allocated CIDR block
- Planning IP allocation across multiple subnets in a VPC
- Generating test IP address lists for load testing or network simulation
Step-by-step Guide
- Step 1: Enter a CIDR block (e.g., 10.0.1.0/24) or a start and end IP address.
- Step 2: Click Calculate to compute the range.
- Step 3: Review the network address, broadcast address, and usable host count.
- Step 4: Copy the IP list or range summary for use in your configuration.
Example
Input
192.168.1.0/29
Output
Network: 192.168.1.0, Broadcast: 192.168.1.7, Usable: 192.168.1.1–192.168.1.6 (6 hosts)
Tips & Notes
- A /32 is a single host; a /30 gives 2 usable addresses — commonly used for point-to-point links.
- Remember to subtract 2 from the total address count for the network and broadcast addresses when planning host capacity.
- Use CIDR notation to specify ranges in AWS Security Groups, GCP firewall rules, and Azure NSG rules.
Frequently Asked Questions
What is the difference between a network address and a usable host address?
The network address is the first IP in the subnet and identifies the subnet itself — it cannot be assigned to a host. The broadcast address is the last IP and is used to send packets to all hosts in the subnet. All addresses in between are usable for host assignment.
Can I calculate IPv6 ranges?
IPv6 ranges are vastly larger (128-bit) and require specialized handling. This tool focuses on IPv4 ranges. For IPv6, use the dedicated ipv6-ula or subnet-calc tools.
IPv4 Range Expander
Calculate the minimal set of CIDR blocks for an IPv4 address range — from start IP to end IP, with block size, host count, and a copyable CIDR list.
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