Subnet Calculator

Subnet Calculator takes a CIDR block like 192.168.1.0/24 and works out the network address, broadcast address, subnet mask, wildcard mask, the first and last usable host addresses, and the total number of usable hosts.

Reach for this when planning how to split a network into subnets, when configuring a router, firewall or DHCP range and you need the exact boundaries of a block, or simply to double check subnetting math by hand.

This covers IPv4 only, and runs entirely in your browser rather than on our server, since it is pure arithmetic on the numbers you provide with nothing to look up or connect to.