| # | Subnet Address | Range of Addresses | Hosts | Split / Join |
|---|---|---|---|---|
| {{ row.id }} | {{ row.cidr }} | {{ row.first }} – {{ row.last }} | {{ row.usable }} |
|
{{ subnetsCSV }}
IPv4 subnetting divides the 32-bit address space into logical segments so different networks can coexist and be routed efficiently. Each segment shares a common prefix, represented by a slash length or equivalent subnet mask, that distinguishes the network portion from the host portion of every address. An accurately chosen prefix balances address conservation with routing clarity across private and public topologies.
The calculator accepts any IPv4 address and prefix length, converts them to binary integers, and applies bitmask arithmetic to derive the network, broadcast, range of usable hosts, and wildcard mask. A reactive engine then renders an interactive bar that lets you split or join subnets visually, updating summaries, JSON, and CSV exports in real time.
Use it when planning a new office network: enter 10.0.0.0/24, split into four equal /26 segments for separate departments, and copy the results directly into router configuration. This avoids manual math errors and accelerates rollout. Always confirm generated ranges against device limits and reserved addresses before deploying to production during change windows.
An IPv4 address is a 32-bit value often shown in dotted-decimal notation. Subnetting treats the leftmost p bits as the network identifier and the remaining (32 − p) bits as the host field. A one-bit mask of length p yields the subnet mask, while its complement forms the wildcard mask. Combining the address with these masks produces deterministic network, broadcast, and host ranges essential for routing decisions and access-control lists.
| Prefix | Usable Hosts | Common Use |
|---|---|---|
| /8 | 16,777,214 | Large public provider block |
| /16 | 65,534 | Campus or ISP region |
| /24 | 254 | Standard LAN segment |
| /30 | 2 | Router link—legacy |
| /31 | 2 | Modern point-to-point |
| /32 | 1 | Host-specific route |
Prefixes shorter than /24 favour many hosts but fewer networks; longer prefixes reverse that trade-off. The calculator highlights the usable-host figure so you can gauge address efficiency instantly.
| Parameter | Meaning | Unit/Datatype |
|---|---|---|
| IP address | Base network identifier | dotted-decimal |
| Prefix length | Bits forming the network part | integer 0–32 |
| Netmask | Binary mask of prefix bits | dotted-decimal |
| Wildcard | Inverse of netmask | dotted-decimal |
| Broadcast | Highest address in subnet | dotted-decimal |
Worked example (192 .168 .1 .0 / 26):
Concepts are defined in RFC 791 (Internet Protocol) and refined by CIDR introductions (RFC 4632). Academic analyses of address efficiency corroborate the host calculations.
This calculation runs entirely in-browser, processing non-sensitive data and requiring no external transmission.
Follow these actions to generate and export a subnet plan efficiently.
Classless Inter-Domain Routing represents the network portion length after a slash, replacing legacy classful boundaries for finer address control.
Wildcard masks are used in many router ACLs; they match host bits inversely to subnet masks, simplifying rule notation.
No. All calculations occur locally in your browser; nothing leaves your device or persists between sessions.
Splitting halves a subnet by incrementing its prefix length. Joining merges two contiguous, equally sized subnets back into their parent block.
This version focuses on IPv4. For IPv6, you need a calculator that supports 128-bit address logic and different host-allocation rules.