OpenIPApi

CIDR calculator

Enter an IPv4 network in CIDR notation (like 192.168.1.0/24) and get every derived value — computed in your browser, nothing is sent anywhere.

How CIDR notation works

The number after the slash counts the fixed bits of the address: /24 fixes the first 24 bits, leaving 8 bits — 256 addresses — for hosts. Two of those (network and broadcast) are reserved, so a /24 gives you 254 usable hosts. Smaller suffix, bigger network.

Common blocks at a glance

A /32 is a single address, /30 is a 4-address point-to-point link, /24 is the classic 254-host LAN, /16 holds 65,534 hosts and /8 over 16 million. Private ranges: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16.

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