About this subnet and CIDR calculator
Calculate IPv4 subnet details from CIDR notation: network address, broadcast address, first and last usable host, number of hosts, subnet mask and wildcard mask. Handy for cloud VNets/VPCs, firewall rules and network planning.
How to use the Subnet / CIDR Calculator
- Enter an IP address with prefix, e.g. 10.0.0.0/24.
- Read the network range, mask and host count.
- Copy any value you need.
Example
192.168.1.0/24 → mask 255.255.255.0, hosts 192.168.1.1 – 192.168.1.254 (254 usable)
Frequently asked questions
How many hosts are in a /24?
A /24 has 256 addresses, of which 254 are usable hosts (network and broadcast are reserved).
Why does Azure or AWS show fewer usable addresses?
Cloud providers reserve extra addresses in each subnet (Azure and AWS reserve 5).
Is my data safe?
Yes. The tool runs entirely in your browser using WebAssembly. Nothing you type or upload is sent to a server, logged or stored.
Is it free?
Yes, completely free with no sign-up, no limits and no watermarks. It also works offline once the page has loaded.