IPv4 Subnet Planner

CIDR

Quick CIDR math for planning, troubleshooting, and documentation. For IPv6, I usually reach for a dedicated calculator, but this one is intentionally fast for the daily IPv4 stuff.

CIDR

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Examples:

CIDR Details

Netmask: 255.255.255.0
Wildcard: 0.0.0.255
Network: 10.0.0.0
Broadcast: 10.0.0.255
Host range: 10.0.0.1 – 10.0.0.254
Addresses: 256 total, 254 usable

Split A Network

Provide a base CIDR and a longer prefix to enumerate child subnets. Output is capped to avoid accidental huge renders.

Base CIDRNew prefixShow first

Generated 16 subnets.

10.0.0.0/24
10.0.1.0/24
10.0.2.0/24
10.0.3.0/24
10.0.4.0/24
10.0.5.0/24
10.0.6.0/24
10.0.7.0/24
10.0.8.0/24
10.0.9.0/24
10.0.10.0/24
10.0.11.0/24
10.0.12.0/24
10.0.13.0/24
10.0.14.0/24
10.0.15.0/24