Calculate IPv4 and IPv6 subnet details including network address, broadcast, host range, netmask, and wildcard mask
Manually calculating subnets is error-prone and slow, especially under pressure during an outage. This calculator handles IPv4 and IPv6 CIDR notation instantly, enter an address, adjust the prefix length, and get network address, broadcast address, usable host range, subnet mask, wildcard mask, and binary representation without touching a spreadsheet.
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You are carving a /24 into smaller segments and need the usable host range for the third /26 block without doing binary math by hand.
CIDR block entered
192.168.1.128/26
Computed subnet facts
Network address: 192.168.1.128 Broadcast address: 192.168.1.191 Usable host range: 192.168.1.129 – 192.168.1.190 Usable hosts: 62 Subnet mask: 255.255.255.192 Wildcard mask: 0.0.0.63
A /26 reserves 26 bits for the network, leaving 6 host bits. 2^6 = 64 addresses per block, minus the network and broadcast addresses gives 62 usable hosts. Block size 64 means the boundaries fall on .0, .64, .128, .192, so .128/26 spans .128 through .191. Every value here is recomputed instantly as you change the prefix length, including IPv6.
Manually calculating subnets is error-prone and slow, especially under pressure during an outage. This calculator handles IPv4 and IPv6 CIDR notation instantly, enter an address, adjust the prefix length, and get network address, broadcast address, usable host range, subnet mask, wildcard mask, and binary representation without touching a spreadsheet.
Right-size subnets when spinning up new VPCs, VLANs, or on-prem segments so you don't waste addresses or run out later.
Confirm the exact CIDR block and wildcard mask before pasting them into ACLs or security group rules.
Verify that two hosts actually belong to the same subnet when diagnosing "destination unreachable" errors.
Practice CIDR-to-mask conversions with instant feedback while studying for CCNA, CompTIA Network+, or similar certs.
Subnetting divides a larger IP network into smaller segments, giving you tighter control over addressing, routing, and security boundaries. The CIDR prefix (like /24 or /27) tells you exactly how many bits belong to the network portion. From there, everything else, usable hosts, broadcast address, wildcard mask, follows from simple binary math that this tool handles automatically. IPv6 subnetting works the same way conceptually, though the address space is vastly larger and /64 is the standard prefix for local segments.
It means the first 24 bits are the network portion. For IPv4, /24 equals a 255.255.255.0 subnet mask with 254 usable host addresses.
The first address is reserved as the network address and the last as the broadcast address, leaving 254 for actual devices.
It's the inverse of the subnet mask, used in Cisco ACLs and OSPF configurations to specify which bits should be matched.
Yes. Switch to IPv6 mode and enter any valid IPv6 address with a prefix length.
This runs as client-side JavaScript. Keys, tokens, payloads, and other inputs never leave your device.