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IPCalc: IPv4 + IPv6 Subnet Calculator
ipcalc for your browser. Paste a CIDR, get the breakdown, plan your splits. Pure client-side math.
Output pastes clean into tickets and docs. Binary column shows the prefix boundary as a gap, ipcalc style. Want to see the bits move, with drills? That's the IPv4 trainer and the IPv6 trainer.
ROOT
Click split on any row to divide a subnet in half.
Click join to merge a leaf with its sibling.
EOF · client-side only · no APIs called