| Label | CIDR Block | Network IP | Usable Host Range | Broadcast IP | Hosts |
|---|---|---|---|---|---|
| Click calculate to partition subnets | |||||
Our free IP Subnet Planner & Calculator provides an interactive network engineering solution to partition IPv4 CIDR blocks, calculate subnet masks, and allocate IP address spaces for cloud VPCs, corporate LANs, and data centers. Choose between two planning strategies: partition by Number of Subnets Needed (e.g., 2, 4, 8, 16) or by Usable Hosts Needed Per Subnet (e.g., 30, 60, 120, 500 hosts). Computes Network IPs, first/last usable host addresses, Broadcast IPs, and RFC 1918 Private vs Public designations. Export complete network subnet tables directly to a subnets-plan.csv spreadsheet. Operating 100% client-side in secure local JavaScript, your internal IP architecture is never transmitted to external servers.
subnets-plan.csv)Type your base IP address (e.g., 192.168.1.0) and choose your parent network CIDR prefix (/24, /16, etc.).
Select whether to divide by 'Number of Subnets Needed' or 'Usable Hosts Needed Per Subnet'.
Inspect the generated subnet allocation table (Network IP, Host Range, Broadcast IP) and export subnets-plan.csv.
Uses 32-bit unsigned integer bitwise math to partition IPv4 blocks without rounding errors or invalid host range overlaps.
Partition network spaces based on required subnet counts or target usable hosts per subnetwork for cloud VPC and LAN planning.
All subnet calculations and CSV exports execute locally in your browser. Internal IP topologies and subnet configurations are never transmitted to any server.
An IPv4 Address is a 32-bit binary integer divided into four 8-bit octets. Subnetting uses bitwise AND logic (\( ext{Network IP} = ext{IP} \mathbin{\&} ext{Subnet Mask}\)) to separate the network prefix from the host identifier bits.
CIDR (Classless Inter-Domain Routing) prefix notation (/24) specifies the number of active network mask bits. Total addresses per subnet equal \(2^{32 - ext{prefix}}\), with usable host capacity given by \(2^{32 - ext{prefix}} - 2\) (reserving network ID and broadcast addresses).
RFC 1918 reserves non-routable private IP spaces (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) for enterprise cloud VPC topologies and local LAN subnetting without public IP exhaustion.