Computes network, broadcast, mask and host range from CIDR.
The Subnet Calculator takes an IPv4 address in CIDR notation (for example 192.168.1.0/24) and computes the network address, netmask, broadcast address, total IP count, and the usable host range. It's handy whenever you're planning IP ranges, configuring routers or firewalls, or double-checking how a /24 or /30 subnet breaks down.
No. The calculation runs entirely in your browser using local JavaScript, and the IP address you enter is never uploaded or transmitted anywhere.
It expects standard CIDR notation: an IPv4 address followed by a slash and a prefix length between 0 and 32, such as 192.168.1.0/24. Invalid octets or a missing prefix produce an error message.
Usable hosts are calculated as the total addresses minus the network and broadcast addresses. For /31 and /32 prefixes there are not enough addresses left for hosts, so the count is zero and no first/last host range is shown.
No. This calculator handles IPv4 addresses only, with prefix lengths from 0 to 32.
Total IPs equal 2 to the power of (32 minus the prefix). Usable hosts equal the total minus 2 (for the network and broadcast addresses), except for /31 and /32 where the usable count is 0.