Tool
CIDR / Subnet Calculator
Enter an IPv4 address and prefix to get the network, broadcast, mask, usable host range and counts. Everything runs locally in your browser.
CIDR
Netmask
Wildcard
Network
Broadcast
First host
Last host
Usable hosts
Total addresses
Class
Scope
Host counts follow the classic rule (network + broadcast are not usable), with the RFC 3021 exception for /31 (2 usable, point-to-point) and /32 (a single host).