IP
Subnet
Calculator

Calculate network address, broadcast address, subnet mask, and usable host range from any IP address in CIDR notation.

IP Address / CIDR

Subnet Details

PropertyValueCopy
Network Address192.168.1.0
Broadcast Address192.168.1.255
Subnet Mask255.255.255.0
Wildcard Mask0.0.0.255
First Usable Host192.168.1.1
Last Usable Host192.168.1.254
Usable Hosts254
Total Addresses256
CIDR Notation/24
IP ClassC

Binary Representation

FieldBinary (dotted octets)
IP Address11000000.10101000.00000001.00000000
Subnet Mask11111111.11111111.11111111.00000000
Network Address11000000.10101000.00000001.00000000
Broadcast Address11000000.10101000.00000001.11111111

Network bits shown in the first 24 positions of the mask.

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Want to understand the binary math behind subnet masks and CIDR notation?

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Frequently Asked Questions

CIDR (Classless Inter-Domain Routing) notation expresses an IP address and its subnet prefix length together. The number after the slash (e.g. /24) indicates how many bits of the address are the network portion. A /24 prefix gives 256 total addresses and 254 usable hosts.

The subnet mask is formed by setting the first N bits to 1 and the remaining bits to 0, where N is the CIDR prefix length. For /24 this produces 11111111.11111111.11111111.00000000 in binary, which equals 255.255.255.0 in dotted decimal.

The wildcard mask is the bitwise inverse of the subnet mask. It is used in access control lists (ACLs) on routers and firewalls to specify which bits of an address must match and which are irrelevant. For a /24 network the wildcard mask is 0.0.0.255.

The first address (all host bits zero) is the network address used to identify the subnet itself. The last address (all host bits one) is the broadcast address used to reach all hosts on the subnet simultaneously. Both are non-assignable, which is why usable hosts = total addresses minus 2 for prefixes /0 through /30.

A /31 subnet contains exactly two addresses and is used for point-to-point links (RFC 3021) — both addresses are usable. A /32 subnet is a host route representing a single specific IP address, commonly used in routing tables and loopback interfaces.

IPv4 addresses are divided into classes based on their leading bits. Class A begins with 0 (first octet 1–127), Class B begins with 10 (128–191), Class C begins with 110 (192–223), Class D (224–239) is multicast, and Class E (240–255) is reserved. Modern networking uses CIDR and mostly ignores classful boundaries.

This calculator supports IPv4 addresses only. IPv6 uses 128-bit addresses and a different subnet model; a dedicated IPv6 subnet calculator is needed for those calculations.