Subnet Calculator & CIDR Visualizer
Calculate IPv4 subnets, masks and host ranges, split blocks (VLSM), and see the network at the bit level.
๐ Runs entirely in your browser. Your input and output are never sent to a server or stored โ fully private.
About this tool
This subnet calculator works out everything you need from an IPv4 address and prefix: the network and broadcast addresses, the usable host range, the subnet mask, the wildcard mask and the total number of hosts. Enter an address in CIDR notation such as 192.168.1.0/24 and it also visualises the network and host bits, so you can see exactly how the mask splits the address.
Frequently asked questions
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation writes an IP address followed by a slash and the prefix length โ the number of bits used for the network part. For example, /24 means the first 24 bits are the network, leaving 8 bits (256 addresses) for hosts.
How many usable hosts are in a /24?
A /24 has 256 total addresses, of which 254 are usable for hosts. The first address is the network address and the last is the broadcast address, and neither can be assigned to a device.
Is my data sent anywhere?
No. The subnet calculator runs entirely in your browser, so the addresses you enter are never sent to or stored on a server.