Bulk Network Address Calculator

Runs the network address, broadcast address, usable range and mask for a whole list of CIDR blocks at once instead of one at a time — the version of the subnet calculator you actually want when you're documenting an entire address plan rather than checking a single block.

The underlying maths, briefly

Given an IP and prefix — 192.168.1.100/24, say — the network address is the IP ANDed with the subnet mask, and the broadcast address is the network address ORed with the inverted mask. Everything between those two, exclusive, is usable — which is why a /24 gives you 254 usable hosts out of 256 total addresses, not 256.

Sizes you'll be reaching for constantly

• /30 — 2 usable — point-to-point router links
• /29 — 6 usable — small server clusters
• /27 — 30 usable — small office segments
• /24 — 254 usable — the standard LAN segment
• /22 — 1,022 usable — a large office or small campus
• /16 — 65,534 usable — enterprise-scale or a full cloud VPC

Where bulk calculation actually saves real time

Documenting firewall rules across dozens of subnets, auditing an IP address management spreadsheet against what's actually allocated, or planning a re-addressing project across multiple sites — doing this one subnet at a time in a single-entry calculator works, but it's slow and it's exactly the kind of repetitive manual task where a typo creeps in on subnet 40-something and nobody catches it until something breaks in production.