Subnet Calculator
Calculate network, broadcast, first and last usable hosts, wildcard mask, and private/public classification. Supports subnet division for VLSM planning.
- Network address
- 192.168.1.0
- Broadcast address
- 192.168.1.255
- First usable host
- 192.168.1.1
- Last usable host
- 192.168.1.254
- Total addresses
- 256
- Usable hosts
- 254
- Subnet mask
- 255.255.255.0
- Wildcard mask
- 0.0.0.255
- CIDR notation
- /24
- Mask (binary)
- 11111111.11111111.11111111.00000000
- Network class
- C
- Classification
- Private (RFC 1918, 192.168.0.0/16)
About this tool
Enter an IPv4 address and a CIDR (or a dotted-quad subnet mask) to compute every value you typically need for subnet planning: network and broadcast addresses, the first and last usable hosts, total and usable address counts, the mask in dotted-decimal and binary, the wildcard mask, and the traditional network class.
The classification field flags private space (RFC 1918), loopback, link-local, carrier-grade NAT (RFC 6598), documentation ranges, and multicast/reserved space. Classful addressing is deprecated for routing, but class context is still useful for diagnostics and for reading older documentation.
The Divide into control produces equal-sized child subnets from the current network — useful for planning VLANs, point-to- point links, or VLSM address allocation. For /31 point-to-point links, both addresses are treated as usable per RFC 3021; for /32 host routes, the single address is usable.
Frequently asked questions
What does CIDR /24 mean?
It means the first 24 bits of the 32-bit IPv4 address identify the network, and the remaining 8 bits identify the host. That leaves 256 total addresses in the subnet and 254 usable for hosts (the first is the network, the last is the broadcast).
How many hosts fit in a /24?
254 usable host addresses. A /24 has 256 total addresses, but the network address and broadcast address are not assignable to hosts.
What is the difference between the network address and the broadcast address?
The network address is the first address in the subnet — all host bits set to 0 — and identifies the subnet itself. The broadcast address is the last address — all host bits set to 1 — and is used to send a single datagram to every host on the subnet.
What is a wildcard mask?
It is the bitwise inverse of the subnet mask. Routers, firewalls, and ACLs (notably Cisco IOS) use wildcard masks to match addresses: a 0 bit in the wildcard means the corresponding address bit must match, and a 1 bit means it can be anything.
Does this calculator work for IPv6?
No, this tool is IPv4 only. An IPv6 subnet calculator is planned as a separate tool.
How do I split a /24 into four /26 subnets?
Select "4 subnets" in the Divide section. The tool lists the four resulting /26 networks with their first and last addresses.