IP Subnet Calculator

Enter an IPv4 address and prefix to get the network address, broadcast, usable host range, mask and host count.

How it works

  • Accepts a prefix length (24) or a dotted netmask (255.255.255.0) — both give the same answers.
  • /31 and /32 links are handled specially, matching how routers actually treat point-to-point and host addresses.
  • Also reports the binary form of the address and mask, which makes the bit boundaries easy to see.