Networking
Enter an IPv4 address and CIDR prefix to compute subnet masks, network range, and host details.
Network Address
192.168.1.0/24
Subnet calculation uses bitwise AND operations on the IP and mask. Network address has all host bits set to 0; broadcast has all host bits set to 1.
An IP subnet calculator is a tool that takes an IPv4 address (e.g. 192.168.1.10) and a CIDR prefix (e.g. /24) and derives the subnet mask, network address, broadcast address, first and last usable host, total number of usable hosts, and wildcard mask. It applies bitwise AND and OR operations to reveal the boundaries and structure of the subnet.
The calculator converts the IP address to a 32-bit binary number and applies the subnet mask (generated from the CIDR prefix). The network address is found by setting all host bits to 0; the broadcast address sets all host bits to 1. Usable hosts exclude the network and broadcast addresses, so a /24 subnet has 2^(32−24)−2 = 254 usable hosts.
Network Address = IP AND Subnet Mask | Broadcast = Network Address OR Wildcard Mask | Total Hosts = 2^(32 − CIDR prefix) − 2The AND operation with the subnet mask isolates the network portion of the IP. The OR with the wildcard (inverted mask) sets all host bits to 1, giving the broadcast address. The 2^(32−prefix)−2 formula counts all possible addresses in the subnet minus the network and broadcast addresses, which cannot be assigned to individual hosts.
| Input | Result | Notes |
|---|---|---|
| IP: 192.168.1.10, CIDR: /24 | Network: 192.168.1.0/24, Mask: 255.255.255.0, Hosts: 254, Usable: 192.168.1.1–192.168.1.254 | A /24 subnet allocates 8 bits to hosts (2^8 = 256 total), leaving 254 usable after excluding network and broadcast. |
| IP: 10.0.0.50, CIDR: /16 | Network: 10.0.0.0/16, Mask: 255.255.0.0, Hosts: 65534, Usable: 10.0.0.1–10.0.255.254 | A /16 (Class B equivalent) has 16 host bits, supporting 65534 usable addresses across 256 subnets of 256 addresses each. |
| IP: 172.16.5.100, CIDR: /30 | Network: 172.16.5.100/30, Mask: 255.255.255.252, Hosts: 2, Usable: 172.16.5.101–172.16.5.102 | A /30 subnet has only 4 addresses total; used for point-to-point links (routers, VPN endpoints) where exactly 2 hosts are needed. |
A subnet mask marks the network portion with 1s (e.g. 255.255.255.0 = 24 consecutive 1s). A wildcard mask is the inverse: it marks the host portion with 1s (e.g. 0.0.0.255 for a /24). Wildcard masks are used in ACLs, OSPF, and some firewall rules.
/32 is a single host. There are no usable host bits, so the network address equals the IP address, and there is only 1 address in the subnet. Used for loopback interfaces and host routes.
This tool is for IPv4 only. IPv6 uses 128-bit addresses and different notation (e.g. 2001:db8::/32). You would need a separate IPv6 subnet calculator.
Supernetting combines multiple subnets under a single larger prefix to reduce routing table size. For example, 192.168.0.0/24 and 192.168.1.0/24 can be summarised as 192.168.0.0/23. This calculator helps identify which subnets can be summarised.
The first address (all host bits 0) is the network address and the last (all host bits 1) is the broadcast address. Neither can be assigned to a host device. A /24 has 2^8 = 256 total addresses but only 254 usable (256 − 2).
RFC1918 reserves three ranges of private (non-routable) IPv4 addresses: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. You should use these ranges for internal networks rather than public addresses.