Your network stays yours.
Address calculations happen in your browser. No analytics, cookies, or third-party scripts. Share links keep the input after a #, which browsers do not send to the server.
NETWORK TOOL NO. 01
Know your network.
From a single address to the whole subnet. Explore IPv4 and IPv6 ranges without sending your input anywhere.
CIDR Lab
IPv4 + IPv6Try
IPv4 NETWORK
Total addresses
Usable hosts
Network / host bits
Address details
Go broader
The containing supernet
Split in two
Two equal-sized subnets
Split to a target prefix
Plan equal-sized subnets within this network. Only 16 entries are generated at a time, even for huge IPv6 ranges.
Select a subnet to inspect it. Copy this page exports only the displayed CIDRs, one per line. Copy link above shares the network, not the plan.
128 bits. No shortcuts.
Integer arithmetic keeps even the largest IPv6 ranges exact. IPv4 /31 uses the point-to-point convention; /32 represents a single host. IPv6 has no broadcast address.
A range, not a route.
This tool does not scan addresses or check reachability. Address counts describe the range, not what your network provider or cloud platform makes available.
A quick guide to CIDR
A prefix tells you how many bits identify the network. The remaining bits identify addresses inside it. A larger prefix means a smaller network.
192.168.1.42/2432 bits − 24 network bits = 8 host bits.
2⁸ = 256 addresses, from .0 through .255.
2001:db8::1/64128 bits − 64 network bits = 64 host bits.
2⁶⁴ = 18,446,744,073,709,551,616 addresses.
IPv6 examples use the documentation prefix 2001:db8::/32. See RFC 4632 for CIDR, RFC 4291 for IPv6 addressing, and RFC 3021 for IPv4 /31 links.