Paste whatever you have — a CIDR block, a bare IP, an IP range, a host count, or an IP-and-subnet pair — and get the answer shaped to the question. Supports IPv4 and IPv6.
I have:
Paste a network in CIDR notation — 192.168.1.0/24 or 2001:db8::/48 — or an IP with a dotted mask: 10.0.0.0 255.255.0.0.
Paste a bare address — 192.168.1.57 or 2001:db8::1 — to identify it (private/public, class, binary) and pick a prefix to see its subnet.
How many usable host addresses do you need? We'll size the smallest subnet that fits.
Enter the first and last address of a range to get the CIDR block(s) that cover it exactly.
Check whether an address belongs to a subnet — handy for firewall rules and routing questions.
Subnet Reference
Prefix
Subnet Mask
Total Addresses
Usable Hosts
Need to manage IP addresses? IPCraft gives you a visual, searchable IPAM.