IP Subnet Calculator
Calculate subnet mask, network address, broadcast address, first and last usable host, and total usable hosts from any IPv4 address and CIDR prefix.
About IP Subnet Calculator
Subnetting divides an IP network into smaller subnetworks, improving security and performance. The CIDR (Classless Inter-Domain Routing) notation specifies the network prefix length — for example, /24 means the first 24 bits identify the network, leaving 8 bits for host addresses (up to 254 usable hosts). For binary conversions related to IP addresses, try our Binary Calculator to understand the underlying bitwise operations.
Network administrators use subnet calculators daily when designing IP address schemes, configuring routers, and troubleshooting connectivity. The wildcard mask (inverse of the subnet mask) is commonly used in access control lists (ACLs). When working with network security, you may also need to generate strong credentials — our Password Generator can help create secure passwords for network devices.
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For a related calculation, use Base64 Encoder/Decoder to encode text to Base64 or decode Base64 strings with UTF-8 support and character count display. Alternatively, use Password Generator to generate cryptographically secure passwords with entropy calculation and strength rating.