Subnet Calculator
v2.10.0
Tool
Split Subnet
Supernet & Route Summarisation
IP Range → CIDREnter a start and end IPv4 address to get the minimal set of CIDR blocks that exactly covers that range using the greedy largest-aligned-block algorithm.
Subnet Allocation Tree
Wildcard ↔ CIDRBidirectional Cisco-style converter. Enter a wildcard mask (e.g. 0.0.0.255) to get its CIDR prefix, or a prefix (/24 or 24) to get the wildcard. Non-contiguous masks are rejected.
Tool
Split Subnet
IPv6 ULA Prefix Generator (RFC 4193)
Tool
Subnet Overlap CheckerCompares two CIDRs and reports whether they overlap, one contains the other, are identical, or have no relationship. Supports both IPv4 and IPv6.
Multi-CIDR Overlap CheckEnter up to 50 IPv4 or IPv6 CIDRs, one per line. The tool reports any pairs that overlap, are identical, or where one contains the other.