Subnet Details
Subnet calculations are a daily task for network engineers, cloud architects, and DevOps engineers configuring VPCs, security groups, and firewall rules. Getting the network address, broadcast address, or host range wrong in a cloud security group can expose infrastructure or block valid traffic. This tool computes all subnet properties from a single IP/CIDR input with no room for arithmetic errors.
The input IP is parsed into a 32-bit unsigned integer by splitting on dots and bit-shifting each octet into position. The subnet mask is derived from the CIDR prefix by setting the top N bits to 1 and the remaining bits to 0 using a left-shift and fill operation.
Network address = IP & mask (bitwise AND). Broadcast address = IP | ~mask (bitwise OR with the inverted mask). First usable host = network + 1. Last usable host = broadcast − 1. Total hosts = 2^(32−prefix). Usable hosts = total − 2. Binary representation converts each of the four octets to an 8-character zero-padded binary string separated by dots.
A cloud engineer configuring an AWS VPC CIDR block verifies that 10.0.0.0/20 provides enough host addresses for 4,000 EC2 instances before committing to the design.
A network engineer writing Cisco ACL rules calculates the wildcard mask for a /26 subnet to correctly scope the permit statement.
A DevOps engineer double-checks that two proposed subnets (10.0.1.0/24 and 10.0.2.0/24) do not overlap before peering two VPCs.
Enter an IPv4 address in dotted-decimal notation (e.g. 192.168.1.50)
Select or type the CIDR prefix length (e.g. /24)
View network address, broadcast, host range, and masks instantly
Toggle binary view to see the full 32-bit binary representation
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