Calculate all IPv4 subnet details from an IP address and CIDR prefix. Network address, broadcast, usable host range, subnet mask in decimal and binary.
Open Subnet Calculator → free, no sign-inIPv4 subnetting is one of those skills that requires either memorisation or a tool. Network address, broadcast address, usable host range, subnet mask in both decimal and binary, number of hosts — all of these follow from an IP address and CIDR prefix, but the calculation is tedious by hand. The Subnet Calculator gives you all of it instantly.
Network engineers, system administrators, DevOps engineers designing cloud network infrastructure, and students studying networking who need reliable subnet calculations.
No tutorials. No learning curve. Open it and get started.
No server uploads. Binary representations are shown alongside decimal — useful for understanding the actual bit-level mask logic.
Completely free. No trial period. No premium tier for basic functionality. No account required. Use it as often as you need.
One job, done well. Subnet Calculator was built to solve a specific problem cleanly. No feature bloat, no ads, no distractions.
What is CIDR?
Classless Inter-Domain Routing notation — /24 means 24 bits for network, 8 bits for hosts.
How many hosts does a /24 give?
256 addresses, minus 2 (network and broadcast) = 254 usable hosts.
How many hosts does a /16 give?
65,536 addresses, minus 2 = 65,534 usable hosts.
What is the network address used for?
The network address identifies the subnet itself — it can't be assigned to a host.
What is the broadcast address?
The last address in the subnet — packets sent to it go to all hosts in the network.
Free. Instant. No sign-in. Open it and get the job done.
Open Subnet Calculator on Doathingy.com →