A Clear Way To Plan IP Blocks
An IP range can look simple at first. Yet one wrong mask can waste addresses. It can also block devices. This calculator helps you inspect a block before you apply it. It shows the network address, broadcast address, subnet mask, wildcard mask, total addresses, usable hosts, and binary form.
Why CIDR Matters
CIDR notation joins an IP address with a prefix. The prefix tells how many bits belong to the network. A smaller prefix gives a larger block. A larger prefix gives a smaller block. For example, /24 is common in small office networks. It gives 256 total addresses. Most normal /24 networks offer 254 usable host addresses.
Range Workflows
Many users start with a first IP and a last IP. This page can summarize that range into exact CIDR blocks. It also shows the smallest covering CIDR block. The exact list is useful for firewall rules. The covering block is helpful for quick planning, but it may include extra addresses outside the original range.
Subnet Planning
Network teams often split one large block into smaller blocks. The new prefix option previews those subnets. It shows the first subnets with their network and broadcast addresses. This helps you reserve spaces for teams, labs, devices, branches, or test environments.
Binary Checks
Binary output is useful when learning subnet math. It shows where network bits stop and host bits begin. This makes mask logic easier to verify. It also helps explain why two addresses fall inside the same block.
Good Practice
Always review usable host counts before deployment. A /31 behaves differently from old host rules. A /32 identifies one address only. Private ranges are best for internal systems. Public ranges need routing, ownership, and careful security controls. Export the result when documenting a change. Keep the saved file with tickets, diagrams, or audit notes. When used with change control, the exported summary reduces disputes. Everyone can see the same mask, range, host count, and subnet split before work begins on live systems.
Final Thoughts
CIDR is compact, but it contains many details. This tool expands those details into readable results. Use it before changing routers, firewalls, DHCP scopes, cloud rules, or monitoring allow lists.