IP Subnet Calculator
Calculate network addresses, subnet masks, and host ranges for IPv4 and IPv6
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Network Topology
About IP Subnet Calculator
IPv4 Calculator
Calculate network addresses, broadcast addresses, subnet masks, and usable host ranges for any IPv4 address and CIDR notation.
IPv6 Support
Full support for IPv6 calculations including prefix lengths, expanded addresses, and massive host calculations for modern networks.
Network Planning
Essential tool for network administrators to plan subnets, allocate IP ranges, and optimize network architecture efficiently.
Private & Public IPs
Automatically identifies whether an IP address is private or public, and determines its class for proper network configuration.
Frequently Asked Questions
A subnet mask is a 32-bit number that divides an IP address into network and host portions. It helps determine which part of an IP address identifies the network and which part identifies the device.
Example: 255.255.255.0 (or /24 in CIDR notation)
CIDR (Classless Inter-Domain Routing) notation is a compact way to specify IP addresses and their subnet masks. It uses a forward slash followed by the number of network bits.
Example: 192.168.1.0/24 means the first 24 bits are the network portion.
The number of usable hosts in a subnet is calculated using the formula: 2^(32 - subnet bits) - 2
We subtract 2 because the first address is the network address and the last is the broadcast address.
Private IP ranges are reserved for use within private networks and are not routable on the internet:
- Class A:
10.0.0.0 - 10.255.255.255 - Class B:
172.16.0.0 - 172.31.255.255 - Class C:
192.168.0.0 - 192.168.255.255