Subnet Calculator

Subnet /24 starting at 192.168.1.0.

How it works

• Parsed the IPv4 address and converted the subnet mask to a prefix length.
• Normalised the address to its network boundary with a bitwise AND.
• Computed the wildcard mask and the usable range 192.168.1.1 – 192.168.1.254.
• Classified the address class and scope for reference.

network = address AND mask

• A non-contiguous subnet mask is rejected rather than guessed.
• /31 and /32 follow RFC 3021 host counting.

Methodology

1. Parse the address strictly and accept the mask as dotted-quad or prefix length.
2. Verify the mask bits are contiguous before using it.
3. Compute network, broadcast, netmask, wildcard, host range and counts as unsigned 32-bit integers.

Usage

1. Enter the IPv4 address.
2. Enter the subnet mask (255.255.255.0) or prefix length (24).
3. Run the calculation and copy the result.

Examples

These are examples, not current values: they use fixed inputs, while the interactive tool computes live results in your browser.

A /24 subnet from a dotted mask

{
  "ip": "192.168.1.10",
  "mask": "255.255.255.0"
}

A /26 subnet from a prefix

{
  "ip": "10.0.0.130",
  "mask": "26"
}

A point-to-point /30

{
  "ip": "198.51.100.9",
  "mask": "255.255.255.252"
}

Limitations

Mask or prefix, same boundary

A subnet mask is the binary boundary between the network and host parts of an address, written as a dotted quad. A prefix length is the number of leading network bits. The two are interchangeable, and this tool accepts either.

Contiguity matters: routers interpret masks as a single run of ones, so a mask like 255.0.255.0 has no defined prefix length and is rejected.