What does Subnet & CIDR Pro do?
Subnet & CIDR Pro calculates the practical values network engineers need when dividing an IPv4 address space: network address, usable host range, broadcast address, subnet mask, wildcard mask, host count, and binary bit layout. Enter an IP address and CIDR prefix to see how the network boundary changes.
Why this tool is useful
Subnetting is the foundation of VLAN design, firewall rules, DHCP scopes, routing summaries, VPN address plans, and cloud VPC layouts. A small CIDR mistake can waste addresses, break route matching, or place systems in the wrong security segment. This calculator makes the boundary visible before you apply a configuration.
Who benefits from it?
Network engineers, CCNA/CCNP students, sysadmins, DevOps engineers, cloud architects, help desk teams, and anyone reviewing an IP plan can use it to verify ranges quickly.
Common use cases
Use it to split office networks, plan server VLANs, check ACL wildcard masks, validate VPC subnets, document customer networks, and explain binary subnet math during training.
FAQ
What is CIDR? CIDR is a compact way to describe how many bits belong to the network portion of an IP address, such as /24 or /27.
What is a wildcard mask used for? Wildcard masks are commonly used in Cisco-style ACL and routing configurations to match address ranges.
Should I use the first and last address? In traditional IPv4 subnets, the first address is the network address and the last is the broadcast address, so hosts usually use the range between them.