IPv4 Subnet / CIDR Calculator
CIDR · IP + dotted mask · bare IP (/32 assumed)
IPv6 Subnet / CIDR Calculator
CIDR notation · bare IPv6 address (/128 assumed) · :: expansion supported
IP Range → Minimal CIDR Blocks
enter start and end IPv4 addresses — generates the minimal set of CIDRs covering the range exactly
CIDR Aggregator / Summarizer
one CIDR per line · overlapping and contained subnets are merged · adjacent same-size subnets are combined
Check: Does IP Belong to Subnet?
enter an IPv4 address and a CIDR block to check membership and position within the subnet