Network Calculator — CIDR, Subnet & Host Range

IPv4 subnets divide address space into routable segments. The prefix length counts leading one bits in the subnet mask — a /24 leaves 256 addresses, typically 254 usable hosts after reserving network and broadcast addresses on classic IPv4 LANs.

Network calculators eliminate manual bitwise AND operations that introduce human error during VLAN design, firewall rule writing, and exam preparation.

The network address has all host bits zero — it identifies the subnet itself and must not assign to hosts on traditional networks. Broadcast address has all host bits one — it targets all hosts on the segment.

Our calculator computes both from your IP and prefix, showing dotted-quad values ready for router configuration templates.

Access control lists on routers use wildcard masks — inverse of subnet masks where zero means must match and one means don't care. The wildcard row helps translate CIDR rules into Cisco-style permit lists.

Security engineers verifying that two CIDR blocks overlap compare network ranges output here before deploying zone-based policies.

Usable hosts subtract network and broadcast addresses on standard IPv4 LANs. A /30 yields two usable addresses common for point-to-point links. /32 represents a single host route.

The calculator displays integer usable counts so capacity planners know how many DHCP leases fit in a scope.

CIDR notation combines network address with prefix length — 192.168.1.0/24 — compact for runbooks and cloud security group rules. Results include fully formatted CIDR string for copy-paste into infrastructure-as-code templates and cloud consoles.

All math executes locally in JavaScript. Internal RFC 1918 addresses, pre-production network plans, and acquisition target schemas never leave your browser — ideal for sensitive design work on untrusted networks.

Entering host IP without recognizing it sits mid-subnet can misalign gateway assumptions. The host range row clarifies first and last assignable addresses.

Mixing /23 boundaries when migrating datacenters causes orphan hosts — preview new prefix before cutover.

Bandwidth calculator converts throughput units on this platform. Bogon checker validates whether addresses are public routable. BGP lookup contextualizes who announces calculated ranges on the internet.

The selector lists every prefix with dotted mask annotation — educational for learners memorizing /26 versus /27 boundaries. Experts jump directly to needed length without mental math.

Certification candidates drill subnetting speed by comparing manual workbook answers against instant calculator verification. Instructors demo live CIDR splits during network courses.