Subnet Calculator
Enter an IPv4 address with a CIDR prefix to compute the network and broadcast addresses, subnet mask, wildcard mask, usable host range and total hosts.
- Network address
- 192.168.1.0
- Broadcast address
- 192.168.1.255
- Subnet mask
- 255.255.255.0
- Wildcard mask
- 0.0.0.255
- CIDR notation
- 192.168.1.0/24
- Usable host range
- 192.168.1.1 – 192.168.1.254
- Total addresses
- 256
- Usable hosts
- 254
- Mask (binary)
- 11111111.11111111.11111111.00000000
About this tool
A subnet calculator takes an IPv4 address and a prefix length (CIDR notation, such as 192.168.1.0/24) and works out every property of that subnet: the network address, the broadcast address, the subnet mask and its wildcard, the first and last usable host, and how many hosts the block contains. It saves you from doing 32-bit binary arithmetic by hand.
Understanding CIDR notation
CIDR (Classless Inter-Domain Routing) writes a network as an address plus a slash and a prefix length — the number of leading bits that identify the network. A /24 reserves 24 bits for the network and leaves 8 for hosts, giving 256 addresses (254 usable). Each step smaller (/23, /22 …) doubles the size.
Network, broadcast and usable hosts
The network address is the first address in the block and identifies the subnet itself; the broadcast address is the last and reaches every host. The addresses in between are usable for devices — which is why a normal subnet has two fewer usable hosts than its total size. (/31 and /32 are special cases used for point-to-point links and single hosts.)
Frequently asked questions
Network engineers use it to plan and document IP address space — determining the network and broadcast addresses, usable host range, subnet mask and host count for a given CIDR block without manual binary math.
It is the CIDR prefix length — the number of bits reserved for the network. A /24 uses 24 network bits and 8 host bits, producing 256 total addresses (254 usable hosts) with a 255.255.255.0 mask.
The first address in a subnet is the network identifier and the last is the broadcast address; neither can be assigned to a device. So a /24 has 256 addresses but 254 usable hosts. /31 and /32 are exceptions.
A wildcard mask is the bitwise inverse of the subnet mask (for /24, 0.0.0.255). It is used in access control lists and routing rules to indicate which address bits should be matched versus ignored.