IPv4 Subnet Calculator
Calculate network, broadcast, mask, usable host range, and boundary cases locally from an IPv4 address and CIDR prefix.
LocalIP addresses are calculated in the browser and are not uploaded.
CIDRBoundary cases such as /31, /32, and /0 stay explicit.
Subnet input
Enter an IPv4 host address and CIDR prefix.
Subnet results
Add an IPv4 address to calculate subnet details locally.
Subnet details
Review masks, host range, and totals before using the plan.
Subnet detail rows will appear here.