IconVault's Subnet Calculator breaks down any IPv4 CIDR block (like 192.168.1.0/24) into everything a network plan needs: the network address, broadcast address, first and last usable host, subnet mask, wildcard mask, total addresses and usable host count. A binary view shows the network, mask and broadcast in dotted-binary so you can see exactly which bits are network and which are host.

Every value has a one-click copy button, and /31 and /32 edge cases are handled correctly. It is free and runs 100% in your browser with nothing uploaded.